The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
Thomas L. Wellborn, Jr. and Charles E. Cichra
Florida Cooperative Extension Service/ Institute of Food and Agricultural Sciences/ University of Florida/ ohn T. Woeste, Dean
L Fa 3L
Catfish fingerling production systems range from simple,
open-pond rearing systems to complex systems where eggs
are incubated in troughs. The complexity of the operation
depends on its size and the producer's objectives.
Channel catfish fingerlings are raised for commercial
food fish production, recreational fee-fishing, and home
use. Some producers sell fingerlings to other producers,
while some limit their operations to supplying their own
needs. A careful study of the market should be conducted
before investing in catfish fingerling production to avoid
losing money because of poor demand.
Whatever the size or purpose of the operation, certain basic
requirements must be met to insure success. Water must be of
good quality and the soil and topography must be suitable for
pond construction. Check with your county Extension agent and
Soil Conservation Service for assistance.
You must have healthy, disease-free catfish brood stock,
suitable ponds for holding brood stock, and in most cases,
nursery ponds for rearing fingerlings. Commercial fingerling
producers usually have separate hatching troughs or tanks
where eggs are incubated and the newly hatched fish, called
"fry," are trained to feed before they are stocked into
nursery ponds. You need tanks supplied with a dependable
water supply and aeration if fingerlings are to be held or
graded before shipment. You-also need seines of suitable
mesh size, length, and depth and a fish transporter to
harvest and transport fry and fingerlings.
Catfish fingerling production requires more technical
skill and management than producing food-size fish from
fingerlings. The fingerling producer must manage the repro-
ductive behavior of the catfish brood stock to meet his
needs and then use specific skills to hatch, rear, harvest,
inventory, and market the fingerlings. The objective is to
produce a given number of fingerlings of a certain size by a
specified time. This requires careful planning, a good under-
standing of the catfish reproductive process, along with an
understanding of the requirements of eggs and young fish.
Most successful operations start small and expand as the
operator gains experience.
Brood Stock Selection
Successful fingerling producers select high quality brood
fish and then care for them properly. This helps insure high
quality and numerous young.
Channel catfish generally reach prime breeding condition
at age three or four years. Young fish are unreliable
spawners. Only about 30 percent of the 2-year-old fish will
spawn. Fish larger than 10-12 pounds are difficult to handle
and have a decreased ratio of eggs per pound of body weight.
Sources and Selection Factors
You may want to buy mature fish nearly ready to spawn
rather than waiting for fingerlings to reach spawning age.
The desirable size for brood fish is 3 to 10 pounds if the
fish have had proper care.
Probably the best source of brood fish is a reputable
hatchery. Be careful not to buy fish that have been discarded
for some undesirable trait. Taking larger fish from heavily
stocked production ponds must be done carefully to make
sure fish with desirable traits are selected. Fish should be
moved into brood ponds before late fall for proper gonadal
Avoid fish recently taken from the wild. They are often
unreliable spawners, and their fingerlings may grow more
slowly and catch disease easier than fingerlings from estab-
lished hatchery stocks. Avoid fish from a source having a
history of channel catfish virus disease. This disease may be
spread from the brood stock to other catfish on your farm.
Check the brood fish carefully before buying, since they
may be old, diseased, or underfed.
Be certain you get the desired proportion of males and
females. A ratio of about three females for every male or
three females for every two males is good. One male can
mate with two or more females in a single spawning season
if the eggs are moved to a hatchery. Although catfish
generally produce offspring in a 50:50 sex ratio, do not
take this ratio for granted in the brooders you buy. Males
tend to grow more rapidly than females, so it is important
to determine the sex of each brooder you buy to insure the
proper ratio of males and females. When catfish reach 2-3
pounds, 80 percent of the largest fish in the population
may be males.
Both primary and secondary sex characteristics are useful
in distinguishing males from females. Secondary character-
istics are those not directly related to reproduction, such as
body shape and coloration. Males are usually larger and
have broader heads than females. As spawning season
approaches, males become lean, develop large muscular
heads, and sometimes become darker, especially the lower
jaw. Females' heads are narrower than their bodies when
viewed from above. They also develop soft, swollen bellies
that are very apparent as the spawning season approaches.
Always confirm sex of the fish by examining the uro-
genital opening, the primary sex characteristic. This is par-
ticularly important with young fish and during the non-
spawning season when secondary sex characteristics are less
pronounced. Experienced producers can accurately sex fish
as small as one pound by examining the urogenital opening.
Turn the fish belly up to examine the genitals. Two or
three openings are present. The opening nearest the head is
the anus, while the one nearest the tail is the genital open-
ing. The genital opening of the male is at the end of a
fleshy, nipple-like structure called the genital papilla, which
usually becomes swollen and rigid as spawning season
approaches. The genital area of the female catfish is oval
and flat and has two openings separated by a small flap of
skin. A slit or groove is located at the tail end. The female
genital area often becomes red, swollen, and covered with
mucus as spawning time approaches.
A probe can be used to distinguish the sexes, particularly
in young fish or those not in spawning condition. A sharp
pencil or straw works well. Immobilize the fish by holding
the fish belly up with one hand grasping the head and the
other hand clasping the fish firmly at the tail region. With
the fish's head just below your chest and the tail held away
from your body, arch the fish's belly upward. This action
causes the male papilla or female genital slit to become
more visible. Then have an assistant gently slide the probe
over the genital area toward the tail, with the point leading
the probe. If the point of the probe catches in the genital
opening, the fish is a female. Also, a straw drawn across the
genital area from the anal fin toward the head catches on
the genital papilla of the male.
Brood Stock Management
Good nutrition is essential to successful spawning. In
warm weather feed a nutritionally complete diet containing
at least 36 percent protein at 1 to 2 percent of the fishes'
body weight daily. Feeding is unnecessary when water tem-
perature is below 500F (100C). When water temperature is
between 500F (100C) and 650F (180C) feed approxi-
mately one percent of the fishes' body weight three days
per week. Feeding activity slows greatly with the onset of
the spawning season. Some producers stock fathead
minnows as a source of additional food for the brood stock.
Just before spawning, the female (right) develops a soft, swollen
belly and the head is narrower than the body. The male (left) has
large, muscular head wider than its body and is often
darker than the female.
To determine sex of brood catfish, look at its belly. You will see
two openings: the one nearest the head is the anus, and the one
closest to the tail is the genital opening. Males can be
distinguished from females by the presence of a fleshy, nipple-like
structure called the genital papilla located just in front of the
Jelly-like mass of eggs
Three types of containers used for spawning
While fathead minnows are good for these purposes, all
other fish, such as bream, carp, shad, and golden shiners
should be avoided (see section on trash fish control).
Total weight of brood fish should not exceed about
1200 pounds per acre at any time of the year. Stock brood
ponds in the spring before spawning season with about 800
to 1000 pounds of fish per acre. This will allow for weight
gain. For good spawning success fish should gain about 50%
of their weight from one spawning season to the next. Each
spring cull undersirable brood fish and replace them with
new brood fish. By replacing old fish with young fish you
can maintain the total initial stocking rate.
The most convenient size for a brood pond is from
one to ten acres. Ponds larger than ten acres are more diffi-
cult to manage. Be sure to keep brood fish in more than
one pond to lessen the risk of losing all fish to a catastrophe
such as low oxygen or disease.
Spawning activity usually begins when the water tem-
perature reaches about 750F (240C) in the spring. Males
nest in hollow logs, spawning containers, or similar protected
places. Females are attracted to the nests and mating begins.
They deposit a layer of eggs that are fertilized by the male.
This process is repeated over several hours until a jelly-like
egg mass of up to two to three pounds, depending on fish
size, is deposited. Female catfish usually produce from
2,000 to 3,000 eggs per pound of body weight, but smaller
females (less than 5 pounds) produce up to 4,000 eggs per
pound of body weight. An average of 3,000 eggs per pound
of spawning female is a good estimate to use for planning
purposes or 10,000 to 11,000 egg per pound of egg mass.
Use of Spawning Containers
Spawning containers should be provided. Such things as
milk cans, nail kegs, earthen crocks, ammunition cans,
wooden boxes, and plastic buckets are used. The spawning
container must be large enough to accommodate the brood-
ing pair. The opening should be just large enough for them
Place the containers in 1 to 2 1/2 feet of water, 1 to 10
yards apart, with the open end toward the pond center.
Mark each one with a float so you can find it. Provide con-
tainers for 50 to 90 percent of the males.
Wait until the water temperature reaches 750F (240C)
before putting out the spawning containers. This discourages
early spawning. Gradually move the containers to deeper,
cooler water as the water warms. Do not use this technique
if the water becomes layered by temperature because the
deeper water will contain little or no oxygen.
Spawning activity sometimes diminishes for no apparent
reason. Lowering the water level about a foot and rapidly
refilling the pond may encourage additional spawning.
Moving the spawning containers may also stimulate spawn-
Considering that not all females spawn and not all of
eggs, fry, and fingerlings survive, estimate that about 1,000
fingerlings will be produced per pound of healthy female
brooder if you use proper brood stock, hatchery, and rear-
Four methods are used in spawning channel catfish in
1. Spawning and rearing pond method. This approach
requires the least skill, labor, and facilities. It is, however,
unreliable and not recommended for commercial operations.
Spawning containers are placed in the pond, and the fish
are allowed to spawn and hatch the eggs. The fry are left in
the pond until ready for harvest.
2. Fry transfer method, open pond spawning. The fry
transfer method is more productive than the spawning and
rearing pond method but requires more skill and labor. The
newly-hatched fry are transferred from the spawning con-
tainers to previously prepared nursery ponds. Check spawn-
ing containers every three days. When an egg mass is found,
gently pinch off a clump of 6 to 10 eggs from the edge.
Determine the age of the eggs to predict the hatching date.
Allow the male to incubate the eggs. Remove the fry one
day after the predicted hatching date. The male catfish can
bite hands and bare feet, so chase him from the spawning
containers with a stick or gloved hand or lift the container
gently off the pond bottom until he leaves.
Transfer the fry to a bucket containing pond water by
gently pouring them from the spawning container after
counting (see section on counting). Release the fry into the
nursery pond by slowly submerging the bucket, allowing
them to escape into the pond near a shelter.
If the water temperature or chemistry is not the same in
both ponds, the fry must be slowly acclimated to the nursery
pond water temperature before stocking. When temperature
differences are more than 2 to 3 degrees, slowly replace
water in the bucket with nursery pond water until the
temperature is equalized.
3. Egg transfer method, open pond spawning. Egg transfer is
the most productive of the four methods, but also requires the
most skill, labor, and facilities. The fish are allowed to spawn in
the containers as with the other methods, but the eggs are removed
and incubated in a hatchery.
Check the spawning containers every two to tour days.
Late afternoon is the best time because most spawning pro-
bably occurs at night or early morning. Checking at this
time does not interrupt spawning activity and allows
for timely removal of eggs. Remove eggs immediately after
finding them. Disturbed brood fish may sometimes eat eggs
or dislodge them.
The egg mass sticks to the container floor. Gently scrape
it free using a plastic credit card, kitchen spatula, or similar
device. Put the egg mass into a bucket and carry it im-
mersed in water to the hatchery. Eggs can be left in buckets
in a shaded area for up to 15 minutes, but no longer unless
you use aeration. Eggs must be shielded from sunlight. Egg
masses near hatching must be taken to the hatchery im-
mediately because they require more oxygen than young or
"green" egg masses. Transporting egg masses in a cooler or
other container can cause egg death due to suffocation.
You should provide aeration if you expect to have a long
time in transport from the pond to the hatchery.
4. Pen spawning. Place a spawning container and a pair
of brood fish in each pen. The fish should be about equal
in size. Check pens from the bank daily for welfare of the
brooders and that the females are not being harassed or
injured by the male fish. Females should be removed imme-
diately after spawning to keep them from being injured or
killed by the male. Do not place more than one female or
male in the pen at a time, since this can lead to fighting and
injury to the females. Eggs can be left with the male or
taken to the hatchery to incubate. If spawning does not
occur in 10 to 14 days, check the sexes of the pair and
exchange brood fish if needed.
In maximum-production systems, eggs are transferred to
a hatchery, incubated, and the fry started on food before
they are moved into nursery ponds. The hatchery need not
be elaborate. The critical ingredient is a water supply of the
right quality and quantity.
Water temperature must be between 75F (24*C) and 82F
(28C) for proper hatching. Because eggs and fry have high oxygen
requirements, maintain oxygen levels at a minimum of six parts
per million (ppm). Water pH must be between 6.5 and 8.5 for
best results. Risk of disease is less if there are no fish in the water
supply. Keep water as clean and free of organic matter such as
algae and decaying leaves as possible. A water flow of about 2
gallons per minute is needed for a 100-gallon hatching trough,
or about one complete water change every 45 minutesto 1 hour.
Well water is probably best for the hatchery. It is usually
clean and free of disease organisms. Well water is usually
too cold for optimum hatching. It can be warmed in a con-
ventional water heater or stored and warmed in a small
pond built specifically for this purpose. Some farmers have
two wells, one from a deep aquifer that has warm water and
one from a shallow aquifer with cold water. A mixing valve
Estimating The Age Of Catfish Eggs'
Blood throughout egg
embryo turns inside shell
Complete fish visible,
no bloody streak
Esiinmled age Estimated da)s
(\aicer al 780F) to hatching
1 to 2 days
2 10 3 dJ,,
3 to 4 days
4 to 5 days
5 to 6 days
7 to 8
6 to 7
5 to 6
4 to 5
3 to 4
2 to 3
6 l., 7 dJj.- 1 to 2
7 to 8 days 0 to 1
* For every 20F above or below 780F, subtract or add one day,
respectively, to hatching time. (H.P. Clemens and K.E. Sneed, 1957.
Spawning behavior of the channel catfish, Ictalurus punctatus. SSR
Fisheries No. 219, U.S.D.I., Fish and Widl. Serv.)
Paddles are spaced so the egg baskets will fit between them.
Egg baskets are made from 1/4 inch plastic-coated hardware cloth.
is used to mix the two in the right proportions to provide
uniform 800F (260C) water to the hatching troughs. The
aeration tank should have a capacity of 25% of the hatch-
eries' entire water volume. This will insure at least a 15-
minute retention time with a 60-minute exchange rate.
Total hardness and total alkalinity should exceed 20
parts per million (ppm), and the pH should range between
6.5 and 8.5. Acidic or soft pond water can usually be
corrected by adding agricultural limestone. Correction must
be designed on a case-by-case basis. Contact your county
Extension agent for assistance.
Although not the best situation, some hatcheries receive water
directly from production ponds. Pond water is usually the proper
temperature for incubation, but may present other problems. Dis-
ease organisms can be introduced to the hatchery from the pond,
especially if fish are present. Algae, suspended mud particles,
and other materials in pond water can accumulate on eggs and
smother them and clog screens. The oxygen content of ponds
often fluctuates, and low oxygen levels, 2 to 3 ppm, are especially
dangerous to fish eggs and fry. Also, late in the spawning season
pond water temperatures often are in excess of 90*F (32*C), greatly
increasing the chances for the occurrence and severity of channel
catfish virus disease.
Incubation Trough Construction
Eggs are commonly incubated in flat-bottomed wooden,
fiberglass, or metal troughs about 8 to 10 feet long, 18 to
24 inches wide, and 10 to 12 inches deep (about 100
gallons). A series of paddles attached to a shaft are sus-
pended in the trough. Paddles are spaced to allow wire-
mesh baskets holding the egg masses to fit between them.
The paddles should reach about halfway to the bottom of
the trough and should extend below the bottoms of the
baskets. Baskets are made from 1/4 inch plastic-coated
hardware cloth. An electric motor with a gear reduction
attachment turns the paddles at 30 rpm. You may use a
direct drive motor turning at 30 rpm. This motion gently
rocks the egg masses and causes oxygen-rich water to flow
through them. An 8-foot trough can hold 6 to 8 egg baskets.
Water enters one end of the trough at a rate that will
allow one complete water exchange in 45 minutes to an
hour (about 2 gallons per minute). A standpipe fitted into a
drain at the other end controls water depth. Place window
screen over the standpipe to prevent fry from escaping.
Check the screen periodically, and clean it if necessary to
keep itfrom plugging, allowing the trough to overflow.
Bacterial diseases and fungus infections are constant
threats to eggs. The best disease control is prevention. A
clean water supply of the proper temperature and frequent
scrubbing and disinfection of troughs and equipment are
essential. Remove debris and egg shells regularly with a
siphon. Check the eggs daily for bacterial egg rot or fungus.
Gently shake the eggs and turn them over twice daily. Bac-
terial egg rot appears as a milky-white dead patch, usually
on the underside and in the center of the mass. Generally
bacterial egg rot occurs when water temperatures are higher
than 820F (280C). The best preventative measure, besides
maintaining good sanitation, is to keep water temperature
at 780F (250C) to 800F (260C).
Fungus grows on infertile or dead eggs usually when the
pond water temperature is below 750F (240C) or hatching
water is below 78*F (250C). It appears as a white or brown cotton-
like growth made of many small filaments that can invade and
kill healthy eggs. You can control fungus by treating with 100
ppm formalin for 15 minutes. Turn the water off during treatment,
but leave the paddles turning. Flush completely with clean water
when treatment time has elapsed. Do not use the formalin treat-
ment when eggs are within one day of hatching. Remember that
bacterial egg rot or fungus seldom causes problems if there is
good aeration and proper temperature. You can avoid most fungal
problems by delaying spawning until the water temperature is
75*F (240C) and keeping hatchery water between 78*F (25"C) and
80*F (26C). If problems develop, get an accurate diagnosis from
a qualified fish pathologist before treating. Determine the under-
lying or primary cause of the problem and correct it to prevent
Handling Sac Fry
Temperature controls incubation time. As the eggs
hatch, sac fry emerge, swim through the screen baskets, and
school together in a tight cluster on the bottom of the
trough. For each pound of egg mass, 10-11,000 eggs will be
present. Approximately 95% of these will hatch. Try to
place egg masses of the same age in the same troughs. This
will facilitate management and help insure good survival.
Sac fry do not eat. They receive nourishment from the
attached yolk sac. The yolk sac is gradually absorbed by the
fry, and after about three days, the fry begin swimming up
to the water surface searching for food. Their color at this
time changes from pink to black. They are called swim-up
fry and begin feeding at this stage.
Sac fry can be left in the hatching trough for one to two
days and then moved to rearing tanks or troughs. Many
types of tanks can be used for holding fry, the most com-
mon in Mississippi being an 8' x 2' x 10" flat bottom
trough which will hold about 100,000 fry. If a large tank is
used, a fry holding box is desirable. This is a 2 x 2 x 1-foot
wooden box made from boards or marine plywood and
caulked with silicone. The bottom is made of 1/16-inch
plastic window screen. One box can hold 20,000 to 30,000
fry, the quantity obtained from a large egg mass. A tank
that can hold 10 fry holding boxes should be supplied with
10 gallons of water per minute.
Siphon the sac fry from the hatching trough into a
bucket using a 1/2-inch hose, and transfer them to the rear-
ing tanks. If you use a fry box, be sure the inlets spray
water directly into the box. Otherwise, low oxygen may
develop inside the box. If it is not convenient to direct
water directly into the fry box, the box should be made of
window screen sewn together and suspended in the water to
allow better water circulation. Attach floats made of
styrofoam or similar material and allow the boxes to float
freely in the tank. This will assure safety of the fry if the
water level in the tank drops. Oxygen in the rearing tank
should remain above five parts per million.
An estimation of fry number is crucial so that rearing
ponds can be stocked correctly. A convenient time to do
this is when they are being transferred to the pond. Two
acceptable methods are the volumetric and weight compar-
ison methods. With the volumetric method count 300 fry
using a fine-mesh aquarium dip net to obtain a representa-
An 8- to 9-foot hatching trough can hold 6 to 10 baskets
with 12 to 20 spawns.
The number of fry being stocked can be estimated by determining
the amount of water displaced by a known number of fry
tive sample and place them in a graduated cylinder con-
taining a pre-measured quantity of water, taking care not to
add any extra water with a fry. Record the change in water
level when you add the fry. You can estimate the total
number of fry by placing all of them in a graduated meas-
uring container, recording the water level change, and then
comparing the two numbers.
Use this equation:
Total number of fry =
300 x change in water level with ALL fry
change in water level with 300 fry
For example, a sample of 300 fry raises the water level
in a 100-milliliter (ml) graduated cylinder from 50 to 62
ml. You will estimate the total number of fry using a larger,
wide-mouthed container also graduated in milliliters.When
you add all the fry the water level changes from 500 ml to
900 ml. Then:
Total number of fry =
300 x (900 500)
or 300 x 400 = 10,000 total number of fry
The fry weighing estimation technique is similar to the
volumetric method except it requires a scale. Water in a
container is weighed and a sample of fry are added (say
300). The increase in weight is recorded. The total sample is
then weighed and a similar formula is used to calculate the
Total number of fr',
.iniple number \ total weight in grams
simple weight in grams
E \jmple sample number= 300 fry
sample weight = 12 grams
total weight of fry = 4000 grams
Total number offer\ = 300 fr \ 14000 grams
Total number of fry = 100,000
Begin feeding the fry when they first swim up to the sur-
face with their mouths opening and heads moving from side
to side, obviously searching for food. "Swim-up" usually
occurs about 3 to 4 days after hatching. Use a high protein
diet (45 to 50 percent crude protein) with all essential
nutrients. Recent findings suggest the protein should
consist of about 60 percent fish meal. The food must be
finely ground so the fry can easily eat it. Commercial cat-
fish fry food is available, but you can use other suitable
feeds such as ground trout feed or salmon starter.
Several feeding techniques are practiced. The most com-
mon technique used is to sprinkle dry food on the surface.
Place the fry feed in a tea strainer and sift the food onto
the surface. This helps distribute the food evenly. The fry
eat the portion that floats. The food can also be moistened,
formed into a doughball, and placed in the fry box or tank.
Whatever the technique, feed the fry at least six times
daily. More frequent feeding, up to one per hour, is better.
Be careful not to overfeed because wasted food accumu-
lates, causing poor water quality and fungus growth. Siphon
out waste and scrub tanks daily. Equipment should be
scrubbed and sterilized with a chlorine solution for 2-5
minutes after each crop of fry. Use one teaspoon clorox
or household bleach per gallon of water, and rinse equip-
ment well in fresh water after sterilization. A minimum of
three complete rinses is necessary.
Water quality in the holding facility determines the
length of time the fry can be held in the hatchery. Fry may
be held for 10 days if you maintain good water quality.
Water quality depends on such factors as water flow rate,
number of fry held, cleanliness maintained, and the chemi-
cal characteristics of the water being used.
Regardless of the length of the stay in the hatchery, all
the fry should be eating food before they are transferred
into nursery ponds. They survive much better in ponds
when stocked as large, strong fry.
The pond should be prepared to receive the fry being
grown in the hatchery. Pond preparation is critical for good
fry survival. Certain aquatic insects and fish eat fry and
must be controlled.
The pond should be filled as soon as possible before stocking
fry and great care should be taken to insure no wild fish are
present in the pond and that none can get in. Proper drainage
structures help prevent their entrance. Filling the pond just before
stocking helps insure that gill-breathing insects don't get a size
advantage on the fry and prey on them.
Treatment to control gill-breathing insects is necessary
when the pond must be filled more than one week before
stocking. A common practice is to spread a mixture of 3 to
5 gallons of #2 diesel fuel or kerosene mixed with one
quart of motor oil per acre over the pond surface 2 days
before stocking (straight #2 diesel fuel will work fine). The
oil film prevents air-breathing insects from penetrating the
surface to breathe. The effectiveness of this treatment de-
pends on complete coverage of the pond surface with oil.
Apply oil when there is no wind or just a light breeze. Con-
tinue this treatment for the first 2 to 3 weeks at 4-day
intervals. A disadvantage of this method is that it does not
kill gill-breathing insects. Do not apply the diesel fuel/oil
before or immediately after feeding, since it can cause fish
kills if ingested with feed.
Controlling Wild Fish
If wild fish are present they may eat all fry placed into a pond.
Draining fry ponds each year and poisoning fish remaining in
potholes eliminates these fish. Rotenone, concentrated chlorine,
or potassium permanganate can be used for this purpose. Contact
your county Extension agent for assistance. If fish are in a pond,
they must be eliminated immediately before stocking fry. Antimy-
cin A can be used to control scale fish. Certain water quality and
technical conditions must be followed for effective treatment.
Contact a fisheries specialist for assistance.
Stock the fry in early morning while it is cool. Gently
transfer them in buckets or fry transport tanks with aera-
tion for large quantities of fry. When using an aerated trans-
porter a maximum of 1/2 pound fry per gallon of water
is acceptable. Condition the fish to the pond water by
slowly replacing tank water with pond water.
Stocking density depends on the size of fingerlings
desired at harvest. Growth rate depends primarily on the
quantity of food the fry and fingerlings consume when
water temperatures and stocking rates are optimum. With
very high stocking densities, it is unsafe to feed the quan-
tity needed for maximum growth for very long because
water quality problems will likely develop.
A maximum feeding rate of 100 Ibs. per acre per day
should not be exceeded in fingerling ponds. It is common
for oxygen depletion to occur when you approach this
feeding rate. Fingerlings do not respond well to emergency
aeration and consequently, massive fish losses occur if you
encounter this problem. If you do not exceed 100 Ibs. per
acre per day you are limited to feeding about 3500 Ibs. of
fish per acre at harvest time. To determine a stocking rate,
divide the anticipated total weight produced per acre by the
weight of the average size fingerling you want to harvest.
Example: Stocking rate/acre needed =
total Ibs. of fish acre
desired e. wt. of fish in Ibs
If 0.06 Ib. aj\rage fish 16 inch) are desired, then:
Stocking rate/acre needed =
0.06 lb. ave. \\ t.
= 58,333 fish
If 0.02 lb. average (4 inch) fish are desired, then:
Stocking rate'acre needed =
0.02 lb. ja e. \%t.
= 175,000 fish
Feeding Fry and Small Fingerlings
Fry and small fingerlings have large appetites and should
be fed frequently, 2 to 3 times daily for the first 2 weeks.
Feed a finely-ground, 40 percent to 45 percent protein diet
the first 3 to 4 weeks. Recent studies suggest that the
protein should contain at least 20 percent fish meal. Switch
to a small-size crumbles of more than 40 percent protein
from 4 to 6 weeks of age and then to a small pellet approxi-
mately 3/16 inch in diameter containing 36 percent pro-
tein. Make sure the particle size is small enough to be
swallowed by the smallest fish so the fingerlings grow uni-
formly. It is better to overfeed slightly in the early stages to
ensure all fry get enough food. Excess feed helps promote
zooplankton growth which can be eaten by fry.
As the fingerlings grow, they eat less food in proportion
to their body weight. However, feeding more than 35
pounds of feed per acre per day increases the probability of
low oxygen problems. It is a "must" in high production
situations to have adequate aeration equipment on standby.
Both floating and sinking feeds are available. Sinking feed
is less expensive, but floating feed lets you watch the feeding
fingerlings. Mixing floating feeds with a sinking type lets you
observe eating and can reduce feed costs. A slow sinking feed,
available commercially, is also suitable.
Feeding activity slows considerable with cool weather. When
water temperature is 45*F (70C) to 550F (13*C), feed 5- to 7-inch
fingerlings about 1 percent of their estimated body weight 3
days per week. Fingerlings fed over winter (November to
March) in the South gain from 25 to 40 percent of their initial
body weight. Smaller fingerlings need more frequent feeding
in winter. Feed them 1.5 percent of their estimated body weight
6 days per week when water temperature is 52*F (11C) to
55*F (13C) and 3 days per week when water temperature is
400F (40C) to 520F (11 C). Adjustments to estimate fish weight
should be made at least weekly to insure feeding percentages
Aquatic weeds and pond "moss" are undesirable in
fingerling ponds. Harvesting fingerlings is very difficult if
weeds collect in seines. Excessive aquatic weed growth can
also cause depressed oxygen levels. The best control is pre-
vention by insuring that a good algal bloom exists. Maintain
a bloom that doesn't allow you to see your fingers when
your arm is in water to the elbow. You can use inorganic
fertilizers to get the desired bloom. If weed problems begin
to develop, control them as soon as possible. Do this by
getting the problem weed accurately identified, selecting
the most effective and economical herbicide that has an
aquatic use label, and treating before the weeds get too
dense. Be aware that any weed treatment could result in an
oxygen depletion and take appropriate preventive measures.
Diseases can be a serious problem for fingerling pro-
ducers. Good management, however, can prevent many
diseases, since many disease outbreaks are related to fish
stress caused by unfavorable environmental conditions,
poor nutrition, and improper handling. When a particular
disease is diagnosed, specific treatments are available.
Some signs of diseases are changes from normal behavior,
reduced vitality, reduced feeding activity, lazy swimming,
and sores. Fish that appear diseased should be sent imme-
diately to a laboratory for diagnostic services.
Select only live fish with disease signs for diagnosis.
Dead, decomposed fish are unusable. Place two to ten
representative sick fish into a strong plastic bag. Put in just
enough water to cover fish. Fill the bag with pure oxygen if
possible and tie securely. Place the bag in a strong, water-
proof box Styrofoamm is best). Pack crushed ice in a sepa-
rate plastic bag and place this bag in the box next to the
fish. Ship the sample by bus or deliver personally. If fish do
not appear strong enough to live through shipment, put
them in a plastic bag and place in a box with ice. Call the
laboratory to advise them of the shipment and to provide
them needed information.
The laboratory will inform you of the diagnosis and
recommend a treatment if needed. Chemical treatments
are generally a last resort and are used only when there is
no alternative. Take every precaution when applying
chemicals. Fish have narrow tolerance ranges for some
chemicals, so very exact calculations are needed. Determine
and record the volume of all your tanks, ponds, and troughs.
Calculating treatment rates is much faster when this infor-
mation is readily available.
Chemicals used for treating diseases should be
thoroughly mixed and evenly distributed from a boat.
Always wear protective clothing and follow label instruc-
Because channel catfish virus (CCV) disease can be such a
serious problem, fingerling producers must be aware of the
potential danger it poses and what can be done to minimize
outbreaks. CCV is a serious disease of channel catfish finger-
lings less than 6 inches long, and it occurs only in summer
when water temperatures are at least 680F (20C) or higher.
There is no treatment for CCV disease, only prevention
and avoidance, which are the keys for minimizing losses.
Here are some steps you can take to prevent outbreaks of
CCV in your fingerlings:
1. Prevent low oxygen stress.
2. Don't allow large number of external parasites to
build up on fingerlings. This can be done by good
3. Handle fingerlings as gently as possible if they must
be moved in summer. (If CCV is suspected, they
should not be moved).
4. Prevent poor water quality conditions from devel-
oping in your ponds and tanks.
5. Do not move fingerlings when water temperatures
exceed 850F (290C).
6. Do not use nets and other equipment that have been
used in ponds or tanks where there is an outbreak of
CCV without first disinfecting in Roccal at 1,000 ppm
for five minutes or HTH (Calcium hypochlorite) at 40
ppm for five minutes.
7. Avoid very high stocking densities, i.e., above 150,000
fry per acre.
8. Do not treat for external parasites until you are cer-
tain CCV is not present.
CCV disease usually occurs in channel catfish fingerlings
following stress when the water temperature is 680F (200C)
or higher. The higher the water temperature, the more
quickly CCV disease can occur and the more losses that
usually occur. Here are some factors that cause stress and
can result in CCV outbreaks in hot weather:
1. Exposure to low oxygen concentration, less than
4 ppm, for an extended period of time.
2. Excessive numbers of external parasites.
3. Rough handling, such as overloading nets or keeping
fish out of the water too long when they are being
4. Poor water quality, such as high levels of un-ionized
5. Moving fingerlings when water temperatures exceed
6. Misused or unnecessary chemical treatments.
7. Overstocking fish.
8. Wild spawning (hatching).
Remember, symptoms are only an indication that CCV
disease may be present and cannot be used to make a posi-
tive diagnosis. If you suspect your fingerlings may have
CCV, have them checked by a qualified fish pathologist.
Good water quality is essential to producing healthy
fingerlings. Low oxygen is by far the most common water
quality problem. Oxygen levels should be above 4 ppm at
all times for fingerlings to grow well. Growth can be
severely slowed when oxygen remains below 3 ppm for long
periods. Stress caused by these conditions can also lower
resistance to disease.
Algae, the tiny plants that give water a green color, pro-
duce oxygen during bright daylight and put it into the
water. However, no oxygen is produced at night, and
respiration of fish, algae, and decaying wastes takes oxygen
from the water. When temperatures are high and fish are
growing rapidly, more oxygen may be taken out at night
than is being produced during the day. Also, cloudy days
may reduce the amount of oxygen produced. The result can
be dead fish. The probability of low oxygen levels increases
with higher feeding and stocking rates. Dissolved oxygen
levels should be monitored daily at dawn and dusk during
warm weather. Oxygen test kits and more expensive oxygen
meters are commercially available and are a worthwhile in-
vestment for the serious producer. Records kept of daily
oxygen readings in each pond can help producers predict
low oxygen problems.
Emergency aeration equipment must be readied when
low oxygen is expected. Probably the most effective device,
especially for ponds larger than 2 or 3 acres, is the paddle-
wheel aerator which may be powered by a tractor or elec-
tricity. It quickly creates a zone of oxygen-rich water where
fingerlings may concentrate.
Some compounds found in water at relatively small con-
centrations are potentially harmful to fish. Copper and zinc
are extremely toxic to fish. Galvanized equipment such as
pipes, containers, screens and tanks may give up enough
zinc to be toxic, particularly when water has a low pH.
Copper from pipes and other equipment can also be toxic
to fish. Metal toxicity can be particularly troublesome in
the hatchery. Use plastic pipe, buckets and other equip-
ment whenever possible.
Catfish are very sensitive to chlorine. Water from city
supplies must not be used in the hatchery, to haul fish, or
to fill ponds unless it is dechlorinated with sodium thiosul-
fate at 7 ppm for each part per million chlorine. Most
municipal water supplies are chlorinated with less than 2
ppm. Pesticides from cultivated land may be a problem in
ponds that receive runoff. Some pesticides are much more
toxic to fish than others. Prevent contamination of the
Oxygen test equipment: dissolved oxygen test kit (above)
electronic oxygen meter (below)
Harvesting and Handling
Harvesting fingerlings is easier in ponds that have clean,
firm bottoms. You should use a mud-line to prevent the
seine from digging into soft, mucky bottoms. The mud-line
also limits muddying the water, which stresses fish, especially
in warm weather.
Up to 75 percent of the fingerlings in a pond can be removed
by trapping them while they feed. Stretch a 100- to 200-foot
long seine parallel to shore at a distance of 30 to 50 feet. Fold
enough netting at the ends of the seine so that the ends can
be pulled to shore without pulling in the main body of the
seine. Tie a rope at each end and lead it to a stake on shore.
The lead-line or mud-line should be in contact with the pond
bottom. Be certain there are no obstructions such as stumps
or logs to snag the seine. Feed the fingerlings inside the trapping
area. After several days the fingerlings will become accustomed
to the seine and will readily enter the area. Pull the folded
ends to shore with the haul ropes when the fish are actively
feeding. Dip the fish from the seine and load directly into
transport equipment. Be sure fish are not full of feed when they
Fingerlings can be partially graded in the pond with the
seine, and final grading is done in tanks with bar graders.
The sharp spines of catfish fingerlings easily become en-
tangled in nylon seines. All nylon seines, nets, and dip nets
should be dipped in an asphalt-base or plastic net coat and
dried before use. This treatment reduces spine snagging.
Polyethylene netting does not need treatment.
Fingerlings can be harvested year-round, except when
water temperatures exceed 850F (290C), if they are
handled quickly and carefully. Handle them only in the
cool hours of early morning. Not handling in hot weather
lessens stress that could bring on an outbreak of channel
catfish virus disease.
Fingerlings are usually graded to various size groups
before shipment. Grading bars, made of aluminum or stain-
less steel rods, are spaced to allow certain size fish to pass
through them. Fish may be sorted through several grading
devices until groups are separated. Grading can be done in
ponds, but holding tanks or vats are best for this operation.
Fingerlings must be counted before transport and sale.
Sometimes fingerlings are sold by weight or by length or by
a combination of weight and length. Graded fish are more
accurately counted than "pond-run" fingerlings that vary in
size. A minimum of three samples with a minimum of 200
fingerlings each are counted and weighed. The samples
Seine Mesh Size and Bar Spacing
For Grading Catfish Fingerlings
Smallest Fish Held Seine Mesh Size Bar Spacing
(Inches) (Inches) (Inches)
should be taken at the beginning, midway, and near the end
of loading. The weight of fish per thousand is calculated
from the sample. All the fingerlings are weighed as they are
loaded into the transport unit and the total number is esti-
mated from the average weight of the individual samples.
For example, three samples are taken of 200 fish each.
Sample weights are 10 ounces, 11 ounces and 12 ounces.
You then have 33 ounces or 2.06 Ibs. per 600 fish. If you
have 500 Ibs. of fish in the tank you can then calculate the
total number of fish in the tank. First convert 33 oz. to
pounds= 2.06 Ibs. sample weight.
Total number of fish =
number of fish in sample x total \ of fish
weight of fish in sample
sample number = 600 fish
sample weight = 2.06 pounds
total weight = 500 pounds
Thus: Total number of fish = 600 fish \ 500 Ibs
Total number of fish = 145,631
To get an estimate on the average size in pounds per
lbs/1000 fish= Total %\ eight in Ibs 1000
total number of fish
total weight = 500 Ibs
total number= 145,631
Thus: lbs/1000 fish= 500 Ibs x 1000
lbs/1000 fish = 3.4
Remember that the average weight of 1,000 fish and an
average number of fish per pound are averages only and the
actual weights and numbers can vary greatly depending on
Fingerlings may be hauled long distances with proper
equipment and care. Use fresh, clean water in the transport
unit. Hauling tanks should be equipped'with electric agita-
tors to oxygenate the water and to release waste gases such
as carbon dioxide and ammonia. Hauling tanks should not
be deeper than 30 inches when only agitators are used. An
air blower or bottled oxygen is needed with deeper tanks or
with exceptionally heavy fish loads. Bottled oxygen is also
a good backup in case the agitators fail.
Oxygen is released into the water through porous dif-
fusers. Small bubbles transfer more oxygen into the water
than large bubbles. A combination of small bubbles from
bottled oxygen and mechanical agitation achieves high
oxygen transfer and good waste gas removal.
The number of fingerlings that can be safely hauled
depends mainly on the volume of water in the transport
unit, efficiency of the aeration system, water temperature,
length of haul, and size and condition of the fish. Hauling
tanks should be insulated to prevent water from over-
heating, particularly on long trips. Chutes attached to quick-
release doors help unload fish with less handling.
Wastes from fish use oxygen and foul the water during
transport, so they should be held in vats, tanks, or socks at
least 12 hours before shipping if transport time will be
longer than 2 hours. This allows time for them to void most
of the waste products from their guts.
Catfish fry can be shipped in 3-mil polyethylene bags.
The bags should have four corners to prevent fry from con-
gregating in collapsed corners where they may suffocate.
Double the bags and place a small quantity of water and
the fish inside, then fill the bags with bottled oxygen. Tie
the bags securely with strong rubber bands. The oxygen
to water volume ratio should be 3:1. Up to 10,000 fry per
gallon can be shipped for several hours using this method.
Fry can also be shipped in conventional haulers, and these
should be used if possible. Be sure to cover the agitator
screens with 1/16 inch mesh screen to keep out the fry.
Although some people add a chemical to the transport
water to prevent disease, no data exist to show this prac-
tice has any real value. The best disease prevention in trans-
port of fingerlings is to make sure they are in good health
when loaded on the truck. Keeping oxygen levels above 4
ppm helps reduce stress in hauling fingerlings. The use of
salt at a rate of 0.05 to 0.1 percent (0.4 0.8 lbs/100 gal-
lons of water) also helps reduce stress during hauling.
To prevent injury to brood fish when hauling small
numbers of them close to spawning season, place individual
fish in wet burlap bags. Large fish are more easily handled
and carried in bags.
Catfish fingerling growth rates may be improved by
choosing the fastest growing fingerlings or food size fish for
future brood stock. This practice, called "mass selection,"
can improve growth rates by 12 to 18 percent and increase
disease resistance. If fingerlings are selected for breeding,
retain additional fingerlings from random samples because
if you select only the largest fingerlings, they may be
mainly faster growing males. Mix the randomly sampled
fish with the large selected fish, and when mature enough,
sex them to ensure you keep the desired proportion of males
Be careful that fish from several different spawns are
selected. Full brother and sister matings can reduce growth
rates up to 7 percent and select for specific disease suscep-
tibilities. Large fish may be from a few early spawns or
from less densely stocked nursery ponds. Therefore, it is
advisable to select potential brood stock from all nursery
ponds, one pond at a time, mixing them only after the
initial selection. Retain fish from enough ponds so that
brood replacement from at least 20 different spawns is
Crossbreeding is an alternative to improve fingerling
quality. First obtain brood stock from established hatcheries.
Keep them separate, and deliberately cross-mate males and
females of separate stocks. Most crossbreeding at research
institutions has produced faster growing fish than either of
the original parent hatchery stocks. Crossbred fish also have
improved disease resistance.
At least three brood ponds are necessary for a cross-
breeding program unless replacement brooders are pur-
chased periodically. Two smaller brood ponds, approxi-
mately 1/2 acre each, are needed to maintain the original
hatchery brood stock. In the third brood pond, males and
females from the respective hatchery stocks are replaced for
crossbreeding. Only males from one stock and females from
the other are placed in this pond to ensure that cross-
Offspring produced by mating the two hatchery stocks
are called F1 crossbreds. They are generally superior to
both parents. The F1 crossbreds also make good brood
stock because they mature early and a larger percentage of
them spawn. However, offspring produced by mating F1
crossbreds to each other have inferior growth and less
disease resistance than their parents. For commercial
operators, getting males form one source and females from
another unrelated source can help prevent inbreeding.
Estimated Fingerling Size After
120-150 DAY GROWING SEASON AT DIFFERENT
Fry stocking density
(fish per acre)
(inches) at harvest
Suggested Feeding Rates for Different Size Catfish
Percent of Body Weight to Feed Daily
at Various Water Temperatures*
Measured at One Foot Depth
Average daily water temp.* F at 1 foot depth
Total length in inches & 650 670 69' 710 730 750 770 790 81o
average number per pound
3" (143/Ib) 1.5 2.4 3.6 4.8 6.0 7.2 8.4 9.6 10.8
4" (53/1b) 1.5 1.8 2.7 3.6 4.5 5.4 6.3 7.2 8.1
5" (29/Ib) 1.5 1.5 2.2 2.9 3.6 4.3 5.0 5.8 6.5
6" (17/Ib) 1.5 1.5 1.8 2.4 3.0 3.6 4.2 4.8 5.4
7" (11/lb) 1.5 1.5 1.5 2.1 2.6 3.1 3.6 4.1 4.6
8" (7/1b) 1.5 1.5 1.5 1.8 2.3 2.7 3.2 3.6 4.1
9"(5/1b) 1.5 1.5 1.5 1.6 2.0 2.4 2.8 3.2 3.6
10"(4/1b) 1.5 1.5 1.5 1.5 1.8 2.2 2.5 2.9 3.2
*To obtain the average daily water temperature take temper iure morning and afternoon each
day and average them.
Average Weight Of Channel Catfish Fingerlings
For Different Lengths
Lengths Average Weight Lbs per
in Inches Thousand Fish
Number of Fish
1 I 1000
2 3 333
3 7 143
4 19 53
5 34 29
6 60 17
7 94 11
8 140 7
9 190 5
10 280 4
Loading Rates In Pounds Of Fish
Per Gallon For Transporting
Various Size Catfish
(Number per pound)
Transportation time (hours)
8hrs. 12 hrs. 16 hrs.
-Loading rates (Ibs fish/gal)-
Rates given are for water temperature at 65F and assume proper
equipment and aeration. Reduce rates by 25 percent for each 100F
rise in temperature.
Adapted from Channel Catfish Fingerling Production by Thomas L. Wellborn, Jr., Mississippi State Cooperative Extension Service,
Publication 1460 with their permission.
Thomas L. Wellborn, Jr. is Professor Emeritus and Charles E. Cichra is Assistant Professor, Department of Fisheries and Aquaculture,
Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.
COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T.
Woeste, director, in cooperation with the United State Department of Agriculture, publishes this information to further the purpose of the May 8
and June 30, 1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and
Institutions that function without regard to race, color, sex, age, handicap or national origin. Single copies of extension publications (excluding
4-H and youth publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state
purchasers is available from C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida 32611.
Before publicizing this publication, editors should contact this address to determine availability. Printed 9/90.