Don't let your pets become pests

Dumping anything out of an aquarium—fish, animals, and plants—can have devastating consequences for Texas' natural waterbodies. This is true for both freshwater and saltwater aquariums. Never dump them into a natural body of water or flush them down the toilet.


the lionfish invasion

What started as a beautiful pet is wreaking havoc on our coastal ecosystem. Lionfish are from the West Pacific Ocean and don’t belong here. They are believed to have been released in Florida by unsuspecting aquarium owners and have been spreading rapidly since. This aggressive and venomous fish can grow up to 19 inches long and has no natural predators here. It has become a major pest causing enormous ecological and economic damage. This invasion has reduced the number of local fish like juvenile grouper and snapper, shrimp and crab species. They can also completely strip reefs. If you see one, report it immediately.

See the whole story on how the Lionfish has become a threat.


Also known as a “suckermouth”, “algae eater” or “armored catfish”, the plecostomus is another example of an aquarium fish that was released into the wild and has grown out of control. They are voracious consumers of aquatic plants and wood, and contribute significantly to erosion in areas of infestation. They also create deep burrows under banks, which cause undercutting and bank collapse. What seems harmless in your tank can be a major threat to the ecosystem outside of it.

plecostomus in aquarium

In the aquarium.

someone holding up a plecostomus outside

Released in the wild.


If you can’t keep your aquarium fish, plants, or animals (snails, shrimp, etc.) anymore, there are responsible alternatives to get rid of them. Plants can be thrown away in the trash, but you’ll need to dispose of your fish and animals more thoughtfully.

fish in a bag

find a new family for your fish

If your fish is healthy, try to find it a new home. You can give it away to a friend with an aquarium, or maybe even the store you bought it from. You can also donate your fish to a school, business or another aquarium hobbyist.

giving a fish

sell or trade your fish

Check around on aquarium forums and blogs online, as someone may want to buy your fish to add to their aquarium, or you may even be able to trade it for something else.

fish angel

humanely euthanize

If you can no longer care for your fish and cannot find them a new home, euthanasia might become an option. There are humane options for ending your fish’s life.

do not drop a fish into the toilet fish gravestone

never flush your fish

Never flush your fish. It’s inhumane because the conditions in the sewer can cause the fish to suffer. The septic system is filled with gases and chemicals that will ultimately poison your fish. It’s hard on your plumbing, too. Ending your fish’s life yourself may sound tough, but it will give it a much more humane death and protect the environment.

Here are some responsible options:
Prepare a euthanasia bath in a tank with one of the following drugs.

Option 1. Prepare a euthanasia bath in a tank with one of the following drugs.

  • Use MS-22 or tricaine methanesulfonate – an FDA approved drug for fish euthanasia. It is sometimes called Finquel or Tricaine-S and can be bought at a pet store. Use 5-10 times the amount the label recommends for anesthesia. This is about 250-500mg/l.
  • Use clove oil: 13 drops per liter of water.

Option 2. Another alternative is to physically kill the fish. This may sound brutal, but it is quick and painless for your fish. To do it, decapitate the fish by holding the head down and quickly severing the head from the body, just behind the skull. Then pith the brain immediately by inserting a sharp knife into the brain between the eyes. Do this quickly to ensure humane treatment.

Larger fish might require the assistance of a veterinarian, depending on the species.

For more information, call Texas Parks and Wildlife Dept. at 512-389-4620 or email

To print or share this information, download the file below.

pdf imageResponsible Ways to Get Rid of Unwanted Aquarium Life
PDF, 123 KB

For more information, call Texas Parks and Wildlife Dept. at 512-389-4620 or email

Download Responsible Ways to Get Rid of Unwanted Aquarium Life  (PDF, 123 KB)