The Texas State Aquarium says a chemical mix-up is to blame for the most significant loss of marine life in its 25-year history.
CNN  — 

A poisonous chemical used in film processing is being blamed for killing almost 400 fish at the Texas State Aquarium.

The chemical got into the Corpus Christi facility’s fish tanks last week by mistake during a parasite treatment. The aquarium director says containers were mislabeled.

The aquarium thought it was using the drug trichlorfon, but instead an “isomer of hydroquinone resorcinol” was used, according to test results.

The National Institutes of Health identifies hydroquinone as a common but toxic chemical that is used in film processing, as a stabilizer in paint and motor fuels, and in cosmetics.

The statement from the Texas State Aquarium did not release the name of the company that supplied the chemicals.

But CNN affiliate KRIS obtained a statement from Fishman Chemical that says it sold the chemical to the aquarium.

Dr. David Fishman, Fishman Chemical’s owner, says he has never had an issue like this before.

“I’m absolutely at a loss of what to say. But I’m waiting to get their sample and test it,” Fishman told the affiliate.

389 fish, including the aquarium’s iconic male sand tiger shark, were killed. The fish inhabited several large habitats, including the Islands of Steel exhibit and the Flower Gardens exhibit.

The tanks are now being decontaminated.

The aquarium, which calls the fish kill “the most significant losses of marine life in our 25-year history,” has been getting donations to help with the recovery.

It says a shipment of fish has already arrived from the Sea Life Aquarium in Grapevine, Texas.

CNN’s Jeremy Grisham contributed to this report