Smithsonian.com

Two of the National Zoo's arapaima fish died recently. Photo by Jessie Cohen.

Two adult arapaima fish died recently at the National Zoo. The first fish died on Thursday, Nov. 19, and the second fish was found dead Friday, Nov. 27. Zoo staff suspect a bacterial infection, and further tests including cultures and microscopic evaluations, should provide staff with further information.

A third adult fish is in poor health and being treated with antibiotics. While staff have observed some improvement, the fish’s prognosis is not yet clear. The zoo’s fourth arapaima, an adolescent, seems to be in good health but is being treated with antibiotics as a precaution. Catfish and pacus also live in the tank and are all in good health.

The two deceased fish lived in the Zoo’s Amazonia exhibit for 16 years. Zoo staff estimate that the two fish were 17 years old. The lifespan of arapaima in captive populations is generally about 17 years.

The arapaima is one of the largest freshwater fish in the world and is native to the Amazon and the Orinoco basin in South America. The fish can grow up to eight feet in length, though the average is between six and seven. The arapaima breathes air and stays submerged for up to 20 minutes at a time. Because the fish stay close to the surface of the water, they are more vulnerable to human hunters. They are a popular food source in South America, and the species is becoming rarer but is not yet endangered.