Sea Anemones and Clown Fish
Among the known biological associations, the most interesting for aquarists is certainly symbiosis.
Among the well known biological associations, the most interesting one is certainly the symbiosis between the genus Amphiprion and several tropical Actiniaria, mainly belonging to the Stoicactiidae family. These sea anemones, like for example all Coelenterates, have on the surface of their tentacles microscopic stinging capsules, usually called nematocysts. These small but numerous structures, although efficient also for defensive purposes, are usually used to capture living prey, such as crustaceans and fish that are within the range of the tentacles. Although even the fish can be stunned and devoured by the Actiniaria, it is not so for the Pomacentrids, which seem immune to the paralysing effects of the nematocysts of their hosts. On the contrary, they live deeply insinuated among the tentacles of the anemones. Among the best known Pomacentridae fish for symbiosis, there are numerous species: Amphiprion (Percula, ocellaris, clarkii, akallopisos, perideraion, melanopus, frenatus, etc.) and Dascyllus trimaculatus and Premnas biaculatus. On the other hand, the anemones that host fish are mainly: Radianthus (Ritteri, malu, simplex, etc.) and Stoichactis.
Besides the symbiosis of the pomacentrids, the symbiosis between a goby (Gobius bucchichii) and an acacia (Anemone sulcata) belonging to the Mediterranean fauna was also observed. Other nice symbiosis exist between Crustacei Decapodi and tropical Actiniaria. These singular forms of cohabitation have given rise to many observations and numerous studies, in an attempt to understand the possibility of existence and characteristics. As already mentioned, although the nematocysts of the Coelenterates can be highly toxic due to their hypnotoxin content and in some cases also fatal to small or even large fish, it is not toxic to small pomacentrids, on the contrary, they come to be even protected. This protection, however, is neither absolute nor permanent, in fact if an Amphiprion is removed from its anemone and kept isolated, it loses its immunity. When, after a certain period of time (more or less long) the clown fish is put back together with the anemone, it is no longer recognised and attacked.
Table with the most common Pomacentrids and their symbiosis.
