Northern Australian is home to many poorly known, range-restricted and potentially vulnerable freshwater fishes. Species with small ranges, low abundances and narrow ecological niches have a ‘triple jeopardy’ extinction risk. I identify fishes with smaller ranges and lower abundances than expected across Australia. In the diverse, highly endemic Kimberley region, I investigate the dietary, habitat and physiological specialization of range-restricted fish. I show that northern Australia contains many potentially vulnerable species, with the Kimberley a hotspot of freshwater conservation concern. Matt is now an environmental consultant.