Parrot fishes are mostly tropical, marine fishes belonging to the family Scaridae under the order Perciformes. The family Scaridae contains 10 genera and about 90 species throughout the world but in India only 16 species under 5 genera are still recorded. These fishes are available abundantly in the shallow reefs of the Red Sea, Atlantic, Indian and Pacific Oceans.

      Parrot fishes are so named for their dentition. Their numerous teeth, arranged in a tightly packed set up on the external surface of the jaw bones, forming a parrot like beak which is used for rasping algae from corals and other rocky substrata.

Feeding habit: -
The parrot fishes are generally herbivorous, but they also eat a wide variety of organisms. Mainly they live on coral reefs. Some species viz., Bolbometopen muricatum include corals (polyps) in the diet. Their feeding activity is also important for the production and distribution of coral sands in the reef and can prevent algae from choking coral. During feeding coral rock is grinded by their pharyngeal teeth and after digestion it is excreted as sands, which may ultimately create a small island. It has been calculated that one parrot fish can chew coral into as much as 90 kg of sand per year.

Colouration: -
Most species are very colourful; adult males and females have different colours. The females usually displaying drab tones of green, brown or grey, while males have a vivid neon colour. The relationship between colour phase and sex is complex, as many species have been shown to be protogynous hermaphrodites (individuals maturing first as females, then sexually transforming into males). This sexual transformation is usually accompanied by a change into colour phase. Most species have two distinct colour phases “INITIAL PHASE” and the “TERMINAL PHASE”. Initial phases may thus be male or female, while terminal phases are invariably male. In most species the juveniles have a different colour pattern than the adults and the juvenile colouration in some tropical species mimic the appearance of other species, at least temporarily.

Behaviour: -
Fights of several females presided over by a single male are the normal phenomenon in some species. The male vigorously defend their position at any challenge. If the dominant male of a troop is removed or died, one of the females will change gender/sex and also adopt the male role. A number of parrot fish species excrete two different types of mucus during day and night. Generally before going to sleep at night, the parrot fish extrudes mucus from its mouth, forming a protective membrane that envelopes as well as secure the fish at a particular location from any predator. This mucus envelop also acts as an early detection system, allowing parrot fish to escape when this protective membrane is disturbed by predators like, moray eel. This mucus has also antitoxidant properties to repair any damage of the body and repel any parasite which when produced during the daytime and also protect the fishes from UV light.

Further reading
1. Bruce, R.W. and Randall, J.E., 1984, Scaridae. In: W. Fischer and G. Bianchi (eds) FAO species identification sheets for fishery purpose. Western Indian Ocean (Fishing Area 51), FAO, Rome, Vol. 3: page var
2. Choat, J.H. and Bellwood, D.R. 1998. Encyclopedia of Fishes, ed. Paxton, J.R. and Eschmeyer, W.N., Academic Press, Sandiego.pp. 209-211.
3. Langerhans, R.B., 2007, Evolutionary consequence of predation: avoidance escape, reproduction and diversification in Predation in organisms: a distinct phenomenon, ed. Elewa, A.M.T. Heidelberg, Germany, Springer-Verlag.
4. Thurman, H.V. and Webber, H.H. 1984, Marine Biology, Chapter 12, Benthos on the Continental Shelf. Merrill Publishing, pp 303-313
5. Videlier H., Geertjes, G.J. and Videlier, J.J.1999, Biochemical characteristics and antibiotic properties on mucus envelope of the queen parrotfish. Journal of Fish Biology, 54: 1124-1127.

Compiled by : Dr. Subrata Kar