As is well known, optimal levels of both homeostasis and welfare of farmed fish are almost completely dependent upon human endeavour to investigate fish brain capacities and utilize them for the greatest benefit. According to the accumulated research experience specifically concerning minimization of farmed fish stress, the final outcome of the involved mechanisms is strongly associated with fish species and biological stage as well as a number of rearing environment parameters related to the type of the production system applied.
Based on the conclusions gained, it is clear that the fish brain-neuroendocrinological system is an extraordinarily rich and expressive one forming a species-specific living ethology that incorporates cognitive behaviour and ‘demands’, the whole constituting, in effect, the fish “personality”. The diverse facets of this ‘personality’ are expressed via a wide range of phenomena: e.g. the power of learning, memorizing, sound production, particular external coloration changes, courtship behaviour, parent care and “emotional feelings” including the manifestation of aggressiveness and the demonstration of “happiness”. The final conclusion to be drawn is that fish are indeed amazing creatures. One can only marvel at the superb plasticity of their brain which, over hundreds of millions of years and through myriad genomic, evolutionary and epigenetic developments, has enabled them to adapt and respond to and remarkably thrive in all extremes of environments, and all this though they lack a cerebral neocortex.