The Thermal Biology Assessment Device (TBAD) employs Counter-Flow Heat Exchange (CFHE) technology within a 2.6-meter acrylic trough to generate precise, stable temperature gradients for evaluating thermal preferences and critical thermal limits in aquatic species. Equipped with multiplexed CFHE conduit assemblies, bubbler systems, and modular arenas, the TBAD facilitates simultaneous multi-parameter thermal assessments in controlled aquatic environments, enhancing research accuracy and efficiency.