New Air Breathing Amazonian Fish
October 15, 2013

New Species Of Air-Breathing Amazonian Fish Discovered

Lee Rannals for - Your Universe Online

A new, air-breathing Amazonian fish reported in the journal Copeia marks the first time a new species of arapaima has been identified since 1847.

Dr. Donald Stewart of the SUNY College of Environmental Science and Forestry discovered the species dubbed Arapaima leptosoma while attempting to reclassify arapaimas, which is among the world's largest freshwater fish.

Arapaimas can grow up to 10-feet in length and weigh 440 pounds. The species is unique because it can breath air through a primitive lung and thrive in oxygen-poor waters. Amazonian people rely on the fish as a critical food source, which has become one of the most important commercial fish in freshwater of the Amazon.

Stewart came across the new species while examining a preserved arapaima at the National Institute of Amazonian Research in Manaus, Brazil. The biologist has been on a quest to study the genus of arapaima in Guyana and Brazil to ensure the taxonomy of the animals so that conservation studies can be properly carried out.

"If each study area has a different species, then results from one area should not be applied to manage populations in the next area," Stewart said in a statement. "Failure to recognize that there are multiple species has consequences that are far reaching."

He said there is a growing aquaculture industry for arapaima, so they are being moved about and stocked in ponds for rearing. Eventually, these fish escape and the ecological effects are then irreversible.

"A species that is endangered in its native habitat may become an invasive species in another habitat. The bottom line is that we shouldn't be moving these large, predatory fishes around until the species and their natural distributions are better known. Given the uncertainties, precaution is needed," Stewart said.

Albert Günther, a scientist at the British Museum of Natural History, published an opinion piece in 1868 suggesting that four species of arapaima were actually all one species. Over the years Günther's point of view became the prevailing wisdom among fish experts, but Stewart set out to determine the facts.

"Until this year, no taxonomist has questioned Günther's opinion about these iconic fishes," Stewart wrote in the journal. "Everybody for 160 years had been saying there's only one kind of arapaima. But we know now there are various species, including some not previously recognized. Each of these unstudied giant fishes needs conservation assessment."

Stewart concluded that all four of the species originally identified in the mid-1800s were distinct, Günther's opinion not withstanding. Stewart believes that his findings will help with arapaima conservation efforts in the future.

Arapaima are among the most historically over-exploited fish species in the Amazon Basin and have been subjected to intense and largely uncontrolled fishing pressure.

"Abundances of arapaima in large expanses of their natural habitat today are near-zero, largely as a consequence of overfishing," said Dr. Leandro Castello, an authority on arapaima in Brazil. "The likely impacts of this magnitude of overfishing on species diversity are not good."

Stewart said the newly discovered species is on display in a public aquarium in the Ukraine. He added that this new species is already being cultured and exported from South America, but under the wrong name.