More than 20 years ago, an intrepid diver ventured deep into the depths of an Oaxaca, Mexico cave system and collected some fish he found swimming in the dark.

That was the start, middle and end of the story as the fish sat in university collections until many years later when two researchers independently decided there was more to be told.

“Everyone forgot about them,” said Prosanta Chakrabarty, associate professor and curator of ichthyology at the LSU Museum of Natural Science. “We just rediscovered it on our shelves.”

The fish represented not only a new species of cave fish, but a new genus as well, according to Chakrabarty, and Stephen Walsh with the U.S. Geological Survey in Florida. The two became partners after they found out they were studying characteristics of the same group of fish collected decades ago.

It’s unclear if the newly identified species is even in the wild anymore because they haven’t been seen since the first discovery and there have been changes to water management — including the building of reservoirs in the area, which might have altered the normally stable cave environment.

“It’s possible it’s still down there,” Chakrabarty said, adding that the hope is the announcement of the classification will get people looking again. “As far as we know, it’s only found in this one cave system.”

The discovery, to be published in the journal Copeia, was done with the help of cave divers who have the expertise to get places, many scientists can’t access.

“Cave divers are an important resource. They’re doing things few people can,” Chakrabarty said. “It’s a very dangerous thing they do.”

Chakrabarty said he and other researchers go into caves and try to study as much as possible, but cave divers go much deeper where animal life exists.

“In this cave, it really was quite deep,” Chakrabarty said.

It’s the latest in about a dozen new species Chakrabarty has already discovered. He will be part of the TED Talk online Thursday and will discus the findings.

“What’s cool about cave fishes is they’ve been isolated from what’s going on at the surface,” Chakrabarty said.

The fish have no color and no eyes, an adaptation after the fish got separated from the surface and became adapted to living in total darkness.

Although relatively small, the fish are the top predator in the cave environment and people don’t pose much of a threat.

“They’re not afraid of anything, so when you go into the cave, they’ll swim right up to you,” Chakrabarty explained.

The discovery was years in the making and born out of curiosity when Chakrabarty was working toward his doctorate at University of Michigan. Walking around the natural history collection, he saw a fish that piqued his interest as being different and it stuck with him until years later he started tracking down other possible examples of the fish. It ended up being on the desk of his co-discover Walsh’s desk so they worked on identifying and writing up the discovery together.

“There’s actually a lot of new species hanging out on shelves in museums,” Chakrabarty said.

Every trip researchers take into the field yields not only the target species they’re looking for, but other animals and plants get collected as well for future study. Once the researchers get back to their university or institution the primary work takes first priority.

“Sometimes (the specimens) end up on the backburner and forgotten,” Chakrabarty said.

Each new species identified can help put a piece in the puzzle of how evolution on the planet moved forward, how species are related and tell us more about the planet’s past.

Follow Amy Wold on Twitter, @awold10