Galaxias tantangara is a small-bodied galaxiid fish listed as critically endangered by the IUCN. Its distribution is highly restricted which likely reflects negative impacts of predation by introduced non-native salmonids, overgrazing and loss of riparian vegetation caused by wild horses and deer, as well as wildfires, and climate change. This species faces a high risk of extinction in the near future unless management actions such as captive breeding and translocation to establish self-sustaining populations are implemented. A captive population of G. tantangara at Charles Sturt University has successfully bred, with juveniles released into a translocation site. However, their low survival rates at the translocation site raise concerns about the species’ persistence and the challenges of optimising their growth and survival after release. Eco-biological data for these species are needed, yet there is limited information available on this. A significant knowledge gap exists regarding the dietary requirements of this species, which are essential for its growth and survival, both in captivity and at potential translocation sites. This research aims to investigate the feeding ecology of G. tantangara. This study tested a non-lethal stomach flushing method to obtain stomach contents from the more common G. olidus and assessed the use of DNA metabarcoding to acquire dietary information from stomach contents and faecal samples. In addition, the study will quantify prey availability and investigate the diet of G. tantangara. Lastly, this research will examine the influence of different feeds on larval and juvenile growth in a captive population of G. tantangara. The findings will contribute to improving the success of translocation efforts and maximising growth in captivity.