Stoplight Parrotfish

Stoplight Parrotfish (Sparisoma viride)

The stoplight parrotfish is a marine ray-finned fish from the parrotfish family. It inhabits coral reefs across Florida, the Caribbean Sea, the Gulf of Mexico, Bermuda, and extends as far south as Brazil. This species primarily feeds on algae, scraping and excavating it with its beak-like teeth. Like many parrotfish, it has the ability to change sex during its life.

The name “stoplight” refers to the distinctive yellow spot near the pectoral fin, which is most visible in males during their terminal phase.

The stoplight parrotfish is a protogynous hermaphrodite, meaning it can change sex from female to male as it matures. This transition is accompanied by significant color changes, controlled by hormones such as 11-ketotestosterone (11-KT). The timing of the sex change can depend on factors like population density, growth rates, and mortality rates. Higher mortality rates or reduced growth in sexually active individuals may trigger earlier sex changes.

The stoplight parrotfish undergoes three distinct life phases: juvenile, initial, and terminal. In the juvenile and initial phases, the fish are brown with a red belly. In the terminal phase, males display vivid green coloring with yellow spots at the base of the tail. Some males may not change color simultaneously with their sex change, resulting in female-mimic males (also known as initial phase males). During the initial phase, approximately 4% of smaller individuals are males.

Stoplight parrotfish are found in shallow, undisturbed coral reefs in Florida, the Caribbean Sea, the Gulf of Mexico, Bermuda, and Brazil. They are diurnal, spending most of the day foraging, swimming, or hovering, and seek shelter under coral boulders at night. Larger individuals tend to swim more and use crevices for shelter, while smaller fish hover more frequently. They are often found in areas with high algal production and are typically site-attached with limited home ranges.