<p>Nanofluids and hybrid nanofluids have received a lot of interest as they have better thermophysical characteristics and heat transfer capacities than conventional fluids. Recently, bioconvective systems with potential uses in engineering and biomedicine have been developed by adding motile microorganisms to nanofluids. However, existing studies on bioconvective heat transfer remain dispersed, with limited critical synthesis of the underlying mathematical models and numerical techniques. This review aims to systematically examine the current state of research on bioconvective heat transfer in mono and hybrid nanofluids, focusing on the mathematical formulations and computational approaches employed. Various thermophysical models, including the Koo-Kleinstreuer-Li model, Buongiorno model and its modified form, Tiwari-Das model, Hamilton-Crosser model, and Yamada-Ota model, are evaluated for their effectiveness in predicting key properties such as viscosity and thermal conductivity. The governing nonlinear differential equations for fluid flow, heat transfer, nanoparticle concentration, and microbe behaviour are all discussed. The study reveals significant trends, difficulties, and research gaps based on the examination of 80 peer-reviewed papers that are indexed in the Scopus database. The results show that, despite ongoing differences in modelling techniques, hybrid nanofluids often provide better thermal performance and flow stability. This work highlights the need for more cohesive and empirically proven models and provides a consolidated reference for future research.</p>