South American fish die at National Zoo
Monday, November 30, 2009; 1:04 PM
Two adult arapaima fish have died at the National Zoo and another is being closely monitored, according to zoo officials.
Officials said the first fish died Nov. 19, and the second was found dead on Nov. 27. A third fish is in poor health and is currently being treated with antibiotics.
A fourth juvenile fish appears to be healthy but is being treated with antibiotics as a precaution, officials said.
Arapaima fish are one of the largest freshwater fish in the world and live in the Amazon and Orinoco Basin in South America. They typically grow between six to seven feet in length and have notable large scales. The arapaima fish had been a part of the Amazonia exhibit at the zoo since 1993.
The fish share a tank in the Amazonia exhibit with catfish and pacus, which, zoo officials said, appear to be unaffected.
Necropsies done on the fish were inconclusive, but officials suspect a bacterial infection could have caused their deaths. Additional tests will be conducted.
Officials said these deaths do not appear to be connected to any apparent malfunctions with the aquatic equipment. Low levels of dissolved oxygen were blamed for the deaths of 11 stingrays and two arowana fish over Memorial Day weekend last May. Insufficient dissolved oxygen in water is the most common cause of fish kills, in both captivity and nature.
The arapaima fish were estimated to be about 17 years old.