CORPUS CHRISTI — A grossly mislabeled chemical container led to last week’s major fish kill at the Texas State Aquarium, according to preliminary test results. 
 
 When aquarium officials added the white powder trichlorfon, a common parasite treatment, to a small test tank containing several fish the results were positive. No deaths. This gave workers the confidence to apply what they believed was the same chemical from a different but identically labeled container to treat parasites in the aquarium’s two largest exhibits, according to Aquarium Chief Executive Officer Tom Schmid. 
 
 Schmid provided additional details during a 2 p.m. news conference at the aquarium. 
 
 The chemical used in the pre-test was not the chemical used to treat the larger tanks. They looked the same. But the second batch was a highly toxic industrial agent Schmid referred to as an isomer of hydroquinone resorcinol, a substance used for film processing and as an additive to paint and fuels. It’s also a known carcinogen, according to the National Institutes of Health, Schmid said. The container had been mislabeled and distributed by Fishman Chemical of Vero Beach, Florida, a wholesale outlet for tropical fish pharmaceuticals. It is unclear whether Fishman manufactures the agent or simply distributes the product, Schmid said. 
 
 The result was an overnight die-off involving about 400 large and small fish, including one of the aquarium’s original and beloved inhabitants, a sand tiger shark named Hans. Others killed include tarpon, grouper, jack crevalle, redfish and dozens of smaller species. 
 
 “We should have done the test with exactly the same batch of drug,” Schmid said earlier this week before learning of the labeling error. 
 
 Meanwhile, the process to replace specimens has begun. Officials from a two dozen aquariums across the United States and one from Singapore have offered to donate fish or help secure specimens. Some have already arrived, while the cleanup continues. 

 Mislabeled Container Responsible for Aquarium Fish Deaths Posted: Tuesday, April 21, 2015 6:13 PM EDT Updated: Monday, April 27, 2015 7:47 PM EDT 
 
 Preliminary test results returned to the Texas State Aquarium Tuesday and point to a mislabeled container that may be to blame for the deaths of hundreds of the Aquarium's fish last week. 
 
 It was a major loss for the Aquarium. It happened last week when staff were treating the tank system for a parasite using a chemical they believed to be trichlorfon. They later discovered that it had an adverse effect on the animals, killing a total of 389 fish, including sharks. 
 
 In all, about 14-percent of the animals housed at the Texas State Aquarium were killed. Staff there are now in the process of cleaning all of the impacted tanks to remove any trace of the toxin. 
 
 During a news conference Tuesday, Aquarium CEO Tom Schmid said preliminary test results showed that it was not trichlorfon that was used, but a totally different chemical that never should have been shipped to the Aquarium in the first place. He said the container was mislabeled. 
 
 "The preliminary results indicate that it was absolutely not that chemical, so somehow during the potentially manufacturing process, or some point in time, that container of medicine was incorrectly mislabeled," Schmid said. "We know that was not trichlorfon. Leads us to conclude that was the cause for the mortality event." 
 
 There is now an investigation into how the wrong chemical arrived at the Aquarium. The actual product used was an isomer of hydroquinine, which is a known blood poison. 
 
 Hydroquinine is an industrial chemical that is used in things like film processing and as a stabilizer in paint, motor fuels and cosmetics. Officials at the Texas State Aquarium said they have sent more samples to a lab for further verification. 
 
 The Aquarium has received overwhelming support and donations from the community. They are hoping once the water is safe that they will be adding a new fish tank system, which could be happening by the end of the week.
– Aquarium workers thought they were treating tanks at the Texas State Aquarium with trichlorfon, a chemical that can be safely used to deal with a parasite that had invaded the tanks. But fish soon began dying, and now the aquarium's CEO says "preliminary results indicate that it was absolutely not that chemical." He tells Kiii News that perhaps "during the manufacturing process, or some point in time, that container of medicine was incorrectly mislabeled." In all, 389 fish—14% of the aquarium's population—were killed. He added that the chemical used—"an isomer of hydroquinine, which is a known blood poison" and is used in paint and motor fuel, according to Kiii—should never have been shipped to the aquarium, and an investigation is underway into how it got there. The aquarium had first tested trichlorfon on a small tank with no ill effects, but when workers treated the larger tanks, they used a "different but identically labeled container," according to the Dallas Morning News. Aquarium staff are cleaning the affected tanks, and once the water is confirmed to be safe, the aquarium plans to add a new tank system—possibly as soon as this week.