U. S. Fish and Wildlife Service
Department of the Interior
Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
Unwtersity of Florida
John T. Woeste, dean
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Any plant or animal that is not native to the United States is
considered an exotic species Most fishes available for
sale in pet shops are exotic and are imported predomi-
nantly from Central and South America. Africa, and south-
east Asia Each year, over 2,000 species, representing
nearly 150 million exotic freshwater and marine fishes, are
imported into the United States for use in the aquarium
trade. Fish culture in Florida also results in millions of
exotic fish available for sale in the ndustr>
Unfortunately, a number of exotic fishes are released into
the wild each year. Hobbyists may not be able to take
their fish with them when they move, or they simply may
lose interest in maintaining an aquarium Fish may also be
released if they outgrow the aquarium or if they appear to
be in poor health. Whatever tie reason, releasing exotic
fish into local waters is not a good idea For one thing, it
may be illegal. But there are sound biological reasons, too:
It Isn't Good for Your Pet Fish
* Released fish will be physiologically stressed upon
introduction to a different environment
* They will be susceptible to parasites and diseases.
* They might be attacked by native predators, such as
larger fish, fish-eating birds or water snakes.
Don't release your pet fish
It Isn't Good for the Environment
* If exotic fish survive and reproduce, they are difficult, if
not impossible to control or eradicate.
* They may cause changes in the existing aquatic com-
munity through competition with native species or
predation on them, as well as through overcrowding or
* They may infect native fish with exotic parasites or
* An exotic may also affect the genetics of native species
by hybridizing with them.
* Sole species may pose a physical or public health
threat, such as piranhas and freshwater stingrays.
Armored catfish, common aquarium algae eaters, are estab-
lished in Florida, Hawaii, Nevada, and Texas.
The oscar, a large, predaceous cichlid, is established in
Florida and expanding its range.
Currently, at least 126 different species of exotic fishes
have been caught in open waters of the United States, and
46 of these are known to have established breeding
populations. Over half of these introductions are due to
the release or escape of aquarium fishes. Because many of
these fishes are native to tropical regions of the world,
their thermal requirements usually prevent them from
surviving in temperate areas. In the U.S., therefore, most
introduced fishes have become established in Florida,
Texas, and the Southwest. Examples include a number of
cichlids, such as the oscar, Jack Dempsey, jewelfish, con-
vict cichlid, Midas cichlid, and spotted tilapia; and
livebearers, such as swordtails, plates and mollies, and ar-
mored catfishes. The goldfish, a native of China, is one of
the few examples of a temperate aquarium species that is
established throughout the U.S.
Swordtails are popular aquarium fish and are estab-
lished in at least seven states.
Alternatives to Release
Instead of subjecting the fish to potentially harmful envi-
ronmental conditions or risking potential ecological
problems by releasing it, there are alternative means for
disposing of unwanted pet fish:
* Return it to a local pet shop for resale or trade.
* Give it to another hobbyist, an aquarium in a pro-
fessional office, a museum, or to a public aquar-
ium or zoological park.
* Donate it to a public institution, such as a school,
nursing home, hospital, or prison.
If these options are not available, a veterinarian or fishery
biologist can euthanize it (put it to sleep) with anesthetic.
You can also do this at home by placing the fish in a
container of water and putting it into the freezer. Because
cold temperature is a natural anesthetic to tropical fishes,
this is considered a very humane method of euthanasia. A
pet shop also may be able to assist you if euthanasia is the
option you choose. An excellent discussion of fish eutha-
nasia was published in the September 1988 issue of
Tropical Fish Hobbyist. This magazine is available through
pet shops or at your local library.
If you must give up your pet fish, please consider its well-
being and its potential impact on the environment. Do not
release it into a natural body of water.
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DON'T RELEASE EXOTICS
,..:. : .For Further
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National Fishery Research Center
7920 N. W. 71st Street
Gainesville, FL 32606
Dawn Jennings or Jim Williams
The Department of Fisheries and Aquaculture
University of Florida
7922 N.W. 71st Street
Gainesville, FL 32606
Your local County Extension Office
First Printing 8-19M-90
COOPERATIVE EXTENSION SERVICE, UNIVERSITYOF FLORIDA,
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T.
Woeste, director, in cooperation with the United States 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 otherservices only to individuals I '
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 contactthis address to determine availability.