Stoplight Parrotfish

The stoplight parrotfish, Sparisoma viride, is one of the most abundant and recognizable parrotfish across Caribbean coral reefs. It displays dramatic differences between life phases: the initial phase, made up of females and some males, is mottled reddish-brown with scattered white blotches, while the terminal phase, consisting of larger dominant males, transforms into a vivid green body with orange-tinted scale edges and a bright yellow patch near the base of the tail resembling a traffic stoplight. Using its fused, parrot-like beak, it scrapes algae from dead coral and rock, contributing to both reef health and sand production through digestion of ingested carbonate material. It is a key grazer helping to keep Caribbean reefs free of overgrowing algae.

• Two distinct color phases: initial phase (female/some males) mottled reddish-brown with irregular white patches; terminal phase (dominant males) bright green
• Terminal males show a crescent-shaped yellow patch near the base of the tail, the namesake 'stoplight' marking
• Orange to pink highlights along scale edges in terminal-phase individuals
• Fused, beak-like dental plate typical of parrotfish
• Medium-sized body compared to larger Caribbean parrotfish like the rainbow or blue parrotfish
• Distinguished from similar green parrotfish by the specific yellow tail-base spot and facial pattern

Stoplight parrotfish are found throughout the tropical western Atlantic and Caribbean, inhabiting coral reefs, reef flats, and adjacent seagrass beds from shallow water down to around 50 meters. They are commonly observed over both live coral and algae-covered dead reef substrate, where they forage during the day. Juveniles often shelter in seagrass beds and shallow reef margins before moving to more exposed reef habitat as they grow. The species is one of the most frequently encountered parrotfish on Caribbean reefs, reflecting its broad tolerance of varied reef zones from shallow patch reefs to deeper fore-reef slopes.

Stoplight parrotfish graze almost continuously during daylight hours, scraping algae and organic film from dead coral and rock surfaces with their fused beak-like teeth; ingested coral rubble is ground down and excreted as fine sand, making the species a significant contributor to reef sediment. They are protogynous hermaphrodites, with many individuals transitioning from female to male as they grow into the terminal phase. Terminal-phase males defend territories containing groups of females and lead spawning rushes toward the water column at dusk. At night, stoplight parrotfish often retreat into reef crevices, where some individuals secrete a protective mucous cocoon believed to mask their scent from nocturnal predators.