The role of intraspecies variation in fish neurobehavioral and neuropharmacological phenotypes in aquatic models

•Zebrafish and other fish models are widely accepted in CNS research and drug screening.•Intraspecies behavioral variation plays a key role in fish drug-evoked responses.•Sex, strain and individual differences contribute markedly to intraspecies variance in fish.•Epigenetics, gut microbiota and gene-environment interactions influence intraspecies variance in fishes.•Here, we outline recent findings and discuss the existing challenges in this field.