Two adult arapaima fish have died in the Amazonia exhibit at the Smithsonian’s National Zoo. The first fish died Thursday, November 19, and a second fish was found dead Friday, November 27. The tank is being closely monitored by Zoo staff as a third adult is in poor health and is currently being treated with antibiotics. Staff have observed a slight improvement but remain guarded about the fish's prognosis. A fourth arapaima, an adolescent, appears healthy, but was started on antibiotics as a preventative measure. The tank is also home to catfish and pacus, which all appear to be in good health.
The gross necropsies (animal autopsy) conducted immediately after the animal deaths were not conclusive in establishing the cause of death, but a bacterial infection is suspected. Additional tests, including cultures and microscopic evaluations, are pending and should provide additional information. Staff confirmed that there were no apparent malfunctions with the aquatic equipment. The fish have lived in the Amazonia exhibit at the Zoo since 1993. Animal care staff approximate their age at 17 years, which is comparable to how long old-aged arapaima live in captivity.
This species of fish is one of the largest freshwater fish in the world and found in the Amazon and Orinoco Basin in South America. Arapaima typically grow between six to seven feet in length and have notable large scales. The International Union for Conservation of Nature last assessed the arapaima population in 1996 and concluded there was insufficient data to make a determination.