In zebra fish, novel diving test, place preference test, light and dark test, predator models, T maze are done to study anxiety, depression, addiction etc. Also models are being customized to study alzheimer, parkinson to study neurological changes in rodent and zebra fish. The relevance of the animal model is selected based on the research outlook of the study. In principle three different kind of animal models are usually preferred to study neurodegenerative disorders: Homologous, Predictive and Isomorphic Model.