Fish and ecology experts are working to prevent the extinction of the tiny and incredibly rare native rainbowfish.

The fish is found in just a few spots in rural North Queensland, and their numbers have been dropping for years due to threats posed by more invasive species.

University of Canberra ecologist Dr Peter Unmack has been studying the rainbowfishes of the Running River north-west of Townsville.

“The Running River Rainbowfish are small, measuring up to 7 centimetres long, and they are only found in one 13 kilometre section of the river,” Dr Unmack said.

“We discovered almost by accident that their limited range is being encroached on by an introduced neighbouring Eastern Rainbowfish species and they appear to be inter-breeding themselves into extinction in the wild.”

Dr Unmack and his colleagues collected more than 100 of the fish, to create a captive insurance population, but needed to confirm that they were genetically pure Running River Rainbowfish before breeding with them.

Dr Unmack and his team have been working with Diversity Arrays Technology (DArT) to genetically test the captive fish, to ensure the population is free from hybrids.

“It an incredible coincidence that we actually caught these two species in the act at this exact time. Five years ago we didn’t have access to the tools to do the genetic work on the scale that we need, and five years from now we wouldn’t expect to find any of the pure Running River Rainbowfish left,” Dr Unmack said.

Public donations, including the support of the Australian New Guinea Fishes Association and aquarist networks in Australia and overseas have allowed some captive fish to be genetically tested so that a pure breeding population has now been established.

“These fish are easy to breed up and because of their popularity with fish keepers, we should be able to conserve them if we’ve acted in time and caught enough pure specimens.”

Dr Unmack is seeking further donations via the UC Foundation to ensure that the entire insurance population of Running River Rainbowfish can be genetically tested.