Stoplight Parrotfish

The stoplight parrotfish, or Sparisoma viride, can be rather hard to identify due to the dramatic phenotypic changes that can occur as the organism matures.  One of the defining features of the Scaridae family, or parrotfishes, is the division of maturity into three phases: a juvenile phase (JP), initial phase (IP), and terminal phase (TP).  In the IP, spotlight parrotfish can be identified by a reddish/brown head and body, a red belly, mixed white scales, and a tan and red crescent shaped tail.  The stoplight parrotfish is usually 5-10 inches in the IP.  When spotlight parrotfish mature to the TP they can be identified by their emerald green color, salmon to yellow markings on the fins, and a small bright yellow spot above the gill.  Stoplight parrotfish in the TP can reach up to 24 inches.

A spotlight parrotfish in the initial phase

Stoplight parrotfish belong to the class Osteichthyes, or bony fishes, and the family Scaridae.  All scarids have powerful jaws, fused teeth that resemble a beak, and bright colors.  Their beaks are used to scrape filamentous algae from coral or even bite into coral itself.  Parrotfish are closely related to the labridae family, or wrasses.  Both parrotfish and wrasses swim predominately with their pectoral fins, are generally dichromatic, and have very complex social mating hierarchies.  Scarids, along with wrasses, are protogynous hermaphrodites.  In other words, all female parrotfish that live long enough change sex.  Fish in the IP are therefore mostly female while fish in the TP are exclusively males.  A typical population of parrotfish contains a few dominant TP males, mostly IP females, and some sexually immature JP fish.

As for stoplight parrotfish, they seem to have a very flexible social structure compared to that of other parrotfish species.  With abundant food sources, the spotlight parrotfish live in non-territorial groups; however, under low resources dominant males become very territorial and reside in a particular part of the reef with several IP females.  These territories are called harems.  When it comes to reproduction, stoplight parrotfish spawn during 90 minute periods throughout the year.    

Stoplight parrotfish also have similar diets to other parrotfish species; they eat mainly filamentous algae, algal bushes, sea grass blades, an occasional crustacean, and sometimes sponge.  Stoplight parrotfish have a tendency to consume more hard coral than other parrotfish species.  Most parrotfish ingest the coral skeleton as a byproduct of consuming filamentous algae; however, stoplight parrotfish frequently take whole bites out of coral.  In fact, they have a five times greater consumption of coral than most parrotfish.  Since calcium carbonate cannot be digested, parrotfish play an major role in creating sand in tropical regions.

References: DeLoach, Ned, and Paul Humann. Reef Fish Behavior: Florida, Caribbean, Bahamas. Jacksonville, FL: New World Publications, 2007. 280-96. Print.; Humann, Paul, and Ned DeLoach. Reef Fish Identification: Florida, Caribbean, Bahamas. Jacksonville, FL: New World Publications, 2002. 192-99. Print.