Sound conservation and fisheries management is underpinned by a thorough understanding of key life-history parameters, including longevity, growth rates, and the age of reproductive maturity. For rare or extinct species, especially those that exist in remote environment s, the study of key life history events presents a logistical challenge or impossibility. In this study we used otolith, scale, and gonadal analyses to investigate how lifespan, growth rates, and age at maturity differ between three rare and threatened taxa of percichthyid fish including the tropical Bloomfield River cod (Guyu wujalwujalensis), the closely related temperate Blue Mountains perch (Macquaria sp. nov. 'Hawkesbury') and Kangaroo River perch (Macquaria sp. nov. 'Kangaroo'). These taxa are both rate and increasingly at risk from extreme disturbances associated with cyclones, fire, floods, and invasive species. Bloomfield River cod exhibited a smaller maximum body size and shorter lifespan (max 136 mm TL, 7 years) than the Blue Mountains perch (229 mm TL, 20 years), and smaller maximum body size than the Kangaroo River perch (233 mm TL, 7 years). Bloomfield River cod had a relative fecundity of 77 – 210 oocytes gram-1 body mass, markedly higher than those of the closely-related Macquarie perch. The life-history data generated in this study provides a foundational contribution to the understanding of these threatened taxa, for which almost no biological information previously existed.