Morphological changes and reproductive costs in brooders of two mouthbrooding freshwater fishes

Parental care purportedly promotes individual reproductive success and improves offspring survival, but is thought to come at a cost the adult carer. Reproductive costs can be physiological such as resources parents spend on caring also morphological changes that are necessary accomplish parental activities. This study considers body condition in brooders of two paternal mouthbrooder fishes – which incubate eggs guard young inside buccal cavity mouth almighty (Glossamia aprion) blue catfish (Neoarius graeffei), from rivers northern Australia. Potential associated with mouthbrooding were examined by quantifying condition, feeding deterrence gut length gill form across individuals varying sex-breeding state category (brooder males, nonbrooder males females). Brooders both species exhibited significantly lower values some indices, did not feed, suggesting reserves being used renewed during mouthbrooding. had shorter lengths than nonbrooders, potentially reduce tissue maintenance time restricted food intake requirements. Both structure compared nonbrooders; indicating structural adaptive plasticity allowing more space for egg brooding cavity. For G. aprion N. graeffei, progeny seemingly required similar trade-offs including nonphysiological activities (e.g. feeding) responses, respiratory digestive morphology, allowed compensate energy expenditure.