In general, the lifespan of a fish is proportional to its full-grown size (not always though). Fishes have different lifespans in home and public aquariums. In the home aquarium, lionfishes can live 12+ years if kept under good conditions. Tangs usually live a few years (if anyone keeps a track of its age), but they are known to live 15+ years in the public aquarium. An interesting thing about clownfishes is their lifespans could triple (12-15 years) if kept in the public aquarium. I think large angels are the ones that usually hold the longevity record (25+ years) in the public aquarium. But, they could live a lot longer in the wild. It would be interesting to know the actual lifespans of fishes in the wild.