A galaxy of Galaxias, where once there was one...

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The number of recognised native freshwater fish species found in Australia is surprisingly low in comparison to other countries at 210, but new research by fish ecologist Tarmo Raadik has increased that number by 15.

PhD student Raadik was not convinced with the findings of a previous study from the early 1980's that seven Mountain galaxias,(Galaxias olidus) variants from various locations between Queensland in the north and Victoria in the south were the same species of fish, despite them all being very similar in size, colouration and marking.

During a decade of observation of these populations he noted differences in behaviour and breeding cycles, so decided to compare tissue samples using DNA techniques.

The results of these tests were remarkable, as they revealed that the 'one' fish was in fact 15 different species.

Raadik feels the study has major implications on the potential increased biodiversity of fish species on the continent which may now have been seriously underestimated. It also highlights the need for greater conservation measures to protect fragmented and isolated populations of Galaxias which have been pushed further and further upstream by trout from not only the introduced fish species, but from drought or bush fire which could now quickly wipe-out some of the newly identified species.

Galaxiids are freshwater fish occurring in cool conditions in the southern hemisphere, particularly in Australia and New Zealand but also in the southern tip of Africa and southern South America. There were around 51 recognised species before this latest study, the largest of which is the Giant kokopu, (Galaxias argenteus) which grows to around 40cm/8in and is native to New Zealand.