Photo courtesy of Nonindigenous
Aquatic Species Program
Don't Release Exotic Fish
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 predominantly from Central and South America, Africa,
and southeast Asia. Each year, over 2000 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 industry.
If you have caught or seen any species that are not native to your area,
please let me know by using the
Exotic fish form. I will also add your sightings and comments
to the bottom of the page.
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 the 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:
- 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.
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 community through
competition with native species or predation on them, as well as through
overcrowding or aggressive behavior.
- They may infect native fish with exotic parasites or diseases.
- An exotic may also affect the genetics of native species by hybridizing
- Some species may pose a physical or public health threat, such as
piranhas and freshwater stingrays.
Current Problems 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 cichlid, such as the Oscar, Jack Dempsey, jewelfish, convict
cichlid, Midas cichlid, and spotted tilapia; and livebearers, such as
swordtails, platies and mollies, and armored 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.
Alternatives to Release Instead of subjecting the
fish to potentially harmful environmental 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 professional office,
a museum, or to a public aquarium 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 euthanasia 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.
Your comments on the alternatives:
I'm on the content team at Montemlife; I wanted to reach out to
you after coming across this article As passionate outdoor enthusiasts
we are on a mission to preserve the beautiful nature we all inherited.
So we put together an in-depth guide on "leave no trace" principles
which will help us to conserve wild places so our kids can enjoy
them too one day.
Here is it:
No Trace Principles
I have a very humane alternative to euthanize your fish, if that
unfortunate event is necessary. Buy pure clove oil. You can get
it at a health food store for under $10 for a Ĺ ounce bottle. Put
the fish in a medium sized mixing bowl in his own water from his
tank. In a small jar or something with a lid (I use a cleaned out
jelly jar) mix the clove oil with tank water. Put the lid on and
shake it like crazy over and over until the liquid in it is white.
Then pour a little into the mixing bowl with the fish. Swirl it
with your hand. The fish might fight it just a little bit and then
slow down. Then pour a little more in and swirl again. He should
just go to sleep and appear dead. If he doesn't, try a little more
of the clove solution, always shaking very well before an addition
to the bowl. When he goes to sleep, leave him in the solution for
a good 10 minutes and then put him in a small cup or zip-lock baggie
and put him in the freezer. Pain free death. Very humane. We should
all go so easily.
This is a rebuttal to Lee's rebuttal. Who knows what fish "feel"?
Less than half a century ago doctors believed babies didn't feel
pain and would do surgery on them without anesthesia. Now they know
otherwise and even a routine circumcision is done with some sort
of topical anesthesia. Most people today would say "duh!" and be
horrified at doctor's past ignorance. Please don't say, PhD or no,
that you KNOW what fish feel. Both logic and common sense, would
indicate that anything with a nervous system feels some sort of
pain and discomfort. And higher, more complicated animals, like
mammals, birds, fish, perhaps even reptiles, are capable of feeling
great distress and pain. To assume otherwise is just silly. We don't
know what animals feel, we often don't even know what each other
feels. Pain is subjective (not relative, but subjective). Pain is
very real, and distressing to anything 'wired' (i.e. a nervous system)
to perceive it. Thus, I think it's safe to say that freezing a fish
is likely to be as uncomfortable and painful as boiling a lobster
(ever hear the high pitched scream they emit?). Let's not rationalize
our actions with inaccuracies. Re: freezing as a form of fish euthanasia,
just say, "of course it's likely to be painful, but we haven't come
up with a better solution yet." And from there, we can find a compassionate
and wise (not releasing them into the wild) solution. Both are important.
This is a rebuttal to the first comment placed on this website.
I honestly believe you are a caring person, but your science is
inaccurate. I am a fish biologist, and let me start of by saying
that Chris is being anthropomorphic by saying that the fish endures
pain by jagged frozen blood cells ripping through veins. No one
knows what the fish is feeling. Actually the cold reduces the fishís
core temperature, slowing down the heart to a stop, itís not as
if the blood freezes into jagged projectiles ripping through veins
at high speeds. In research we commonly euthanize fish in this manner,
other methods include using a sufficient dose of MS-222, or the
less commonly used pithing of the fish with a sharp needle to the
brain. There is no magic on/off switch for a fish. Having an exotic
species of pet is a responsibility everyone should take seriously.
You need to ask yourself, if you love your fish why do you want
to get rid of it in the first place, and also do you realize by
saving your one fish by releasing it into the wild actually threatens
many native species, you may be killing more fish in the future
then you could dream of. Also, Chris your last sentence is hypocritical;
you stated: Whether you chose to believe this or take this suggestion
off your site is up to you, but I would personally rather release
a fish than freeze it, and I don't believe in releasing exotic fishes
either. O.K. you would rather release a fish than freeze it, but
you donít believe in releasing exotic fishes, so what would you
rather do than releasing it? As far as I know it is not illegal
to release native fishes in their native habitats.
I've studied a lot about fish since I first got into fish keeping
and I read something on your site I simply must make a comment about.
You talk about saving the environment, and being humane while doing
it yet when you mention fish euthanasia you say putting a fish in
a freezer is a humane form of it. This is not true, cold temperature
is not an "anesthetic" to tropical fishes. Tropical fish slow down
because they get their body temperature from surrounding water so
the cold makes them slow, so in a sense this could be considered
an anesthetic of sorts, but not truly. While the fish appears to
just "slow down and go to sleep" it is actually in a great deal
of pain. The cold itself is very painful to the fish and when the
actual freezing of the water starts the fish is still alive and
conscious enough to feel the pain. As the fish freezes its blood
cells freeze in jagged spiky balls ripping through the veins, organs,
etc. Whether you chose to believe this or take this suggestion off
your site is up to you, but I would personally rather release a
fish than freeze it, and I don't believe in releasing exotic fishes
Your sightings and comments:
Fish sighted: Texas cichlid
Location: Hidalgo County Irrigation Canal, TX.
Fish sighted: Oscars, other cichlids, Asian catfish
Location: Florida, Big Cypress National Preserve L-28
In Florida, seeing
exotics is a normal occurrence. I have been fishing for native
sunfish, and then catch Mayan Cichlids (released in 1983), Jaguar
Guapotes (released in 1995), Oscars(not sure of release date),
and countless Asian catfish. I believe that it is despicable that
people release these fish. Mayans are proven to scare away largemouth,
and tilapia overwhelm the Everglades. So if you have a fish that
you do not want, PLEASE, give it away or euthanize it humanely.
Do it for the natives!
Fish sighted: Oscar, Plecos, Peacock Bass, Tilapia
Location: Texas, San Antonio River
San Antonio River.
Brackenridge Park near the SA Zoo. Numerous exotics I have caught
using a cast net including huge plecos, Oscars, Pacus, Peacock
Bass, Mozambique tilapias, and even a 20''+ Koi. The waters of
the SA river run right through the zoo, which could explain the
tilapias and such because the zoo has them all over the place
in their waters to eat hippo dung and such. I never but fish for
my 7000 gallon pond I built. I just go to the park with a cast
net, throw some bread in the water and wait a couple minutes and
throw my net. Then I transport them to my pond. Several beautiful
Koi are now in my pond well over 20''!!! I have all the fish named
above in my homemade pond.
Fish sighted: Clown knife fish, butterfly peacock bass
Location: Florida, West Palm beach
While fishing with
my dad on November 24,2006 at 4:30 we were fishing some rip rap
for largemouth bass when something hit my dads bait and he told
my to get the net because it was a big one when I went to net
it it was a clown knife fish and it wouldn't even fit in our net
it was 28 inches long and weighted 10.5 pounds on digital scales
and just 15 minutes later I caught a butterfly peacock bass on
a crankbait it was 15 inches long and weighted 2.7 pounds both
fish were caught on bomber Fat A crankbaits in firetiger and shad
From: Tim Shelton
Fish sighted: Oscar
Location: North Carolina, Local pond
Caught 12" Red
Oscar while fishing for largemouth bass in a local pond in Hendersonville,NC
using a 2" salt impregnated tube style bait.
Fish sighted: oscar
Location: Lake Woodlands, north of Houston TX
My cousin and his
friend where fishing in a man made lake in The Woodlands, 35 miles
north of Houston. His friend caught what appeared to be an Oscar-hybrid.
It was about 8 inches long and looked like an Oscar but had a
forked tail. He put it in his aquarium with another Oscar he already
had. It lived quite sometime. I've also seen mollies, goldfish,
various African and south American cichlids and gouramies in other
man-made lake in The Woodlands. Seems like a lot of people there
are releasing unwanted fish.
From: Robert Boland
Fish sighted: Oscar
Location: Fort Gordon, Georgia
I was bass fishing on Fort Gordon, Georgia
at my favorite lake. At first glance, I thought a bluegill was
following my large bass lure. At second glance, I could see this
was no fish I had ever seen before! I tied on a small jig, and
caught him. One of my friends identified him as an Oscar, for
he has a few at home himself. Because I caught the fish right
next to the dam (a road is on the dam) I can only assume he got
too big for someone's tank.
Fish sighted: Cichlids
Location: Florida, Everglades
You name it, they are here. Oscars were
big for a while but have now been eaten almost clean out of the
habitat by the Uropthalmus. I have caught Tilapia Mariae, walking
cats, Port cichlids, etc.... Its the Uropthalmus that's the worst.
I stopped and saw some the other day. In a single 10' x 10' area,
one foot deep, there were 40 breeding pairs with spawns. I never
thought they would tolerate each other that close. The nests were
literally a foot apart. And this was in a canal off of rte 41
in the middle of the everglades. There were likely tens of thousands
of them within a quarter mile of me. A horrible fish.
From: Loring Chien
Fish sighted: Goldfish
I was somewhat surprised and have now
seen this TV commercial several times. I'm referring to a Blue
Cross, Blue Shield of Texas ad shown in Houston and I'm sure some
other places in Texas. The gist of the commercial is a boy wanting
to set something free and ends up in the last frames showing the
boy emptying a goldfish bowl with goldfish into a natural pond
or lake. This struck me as a very bad image to be showing on TV
as other children might try to emulate this on their own with
god knows what fish they find at home. I guess the bad things
are one, showing the act and two, glorifying it as something desirable
to do. Couldn't find an e-mail address on the blue cross site
that I could sent to without an health account.
Fish sighted: oscars, cichlids, pleco
Location: Florida, Various drainage canals, Miami area
Hello, I used to live in the Miami area
for several years and caught at least 3 species of cichlids along
with oscars while fishing for native gamefish on rod and reel.
Also, have used small cichlids (less than the size of my hand)
for bait to capture quite a few snook and tarpon in the drainage
canals and other small interconnecting lakes. Have also seen some
truly monstrous (20 inches!) plecos living on/in the many culvert
pipes and headwalls constructed to carry the water under the roads.
I have also caught a couple of peacock bass that were supposedly
released by the Florida DNR to help control the exotics. By the
way, when fishing for crappies with 4# test, an oscar gives good
account of itself on rod and reel. The peacock bass is a great
fighter, also. Pound for pound I don't think they match a tarpon.
Not much can.
From: Grace Hoffman
Fish sighted: Jack Dempsey
I have to write on people releasing exotic
fish in waterways. I brought my daughter last week to go fishing
at our local park and I happened to catch a jack dempsey there
and he is about 6 inches long. When I caught him I new immediately
what kind of fish it was so I grabbed my bucket out of the back
of my car and now, a week later the fish is still alive in my
55 gallon tank where it will stay. It is stupid for people to
release these fishes in the wild because down here in Louisiana
they will adapt real easy and eat all of our native fishes. So
by catching this fish I was able to explain to my 4 yr old by
way of example that it is not good to let them go in the wild,
that it is better to bring it to the pet store. Click to see a
I received this email it applies to these fish:
I was surfing and came across your page.
Critical issue! I am a supporter of the NAS, an avid member of
the American Cichlid Association and the Texas Cichlid Association.
Just a minor correction to the above sighting. The fish pictured
is a Cichlisoma (Herichthys) cyanogattatum AKA Texas Cichlid.
While I have not heard of one being caught in LA, we have had
many reported sightings of native populations as far north as
Austin. Likely this specimen was transported and released or through
some other form of contamination of the water supply. Just thought
you might want to accurately identify the Interloper.
Keith D. Pearson
Vice President Pearson Interests
O- (214) 522-7663
HERE FOR MORE SIGHTINGS AND COMMENTS
Information was graciously provided by the Nonindigenous Aquatic Species
Program and the U.S. Geological Survey. Please click on their logos for
much more information.