Mislabeled Chemical Blamed in Aquarium Die-Off 14% of Texas State Aquarium's population killed By Evann Gastaldo, Newser Staff Posted Apr 22, 2015 8:51 AM CDT 6 comments Comments The Texas State Aquarium in Corpus Christi is shown. (AP Photo/Corpus Christi Caller-Times,) (Newser) – 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.