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Today on Animal Fact Files we’re discussing the royal gramma and its relatives. There are four other species in the Gramma genus. They're all commonly known as basslets, including the royal gamma which is also called the fairy basslet, but since the common name “basslet” is used in other fish genera, we'll stick to “gramma” since that's this genus's scientific name as well! These are small fish, typically no longer than 3 inches (8 cm) long. Male grammas are slightly larger than females, but they otherwise display no further sexual dimorphism. Grammas have a blunt nose and big eyes as well as a continuous dorsal fin, which is the fin that runs along their back.

The royal gramma is purple and yellow. As their bright colors may suggest, these are reef fish. Grammas often live in crevices and cracks in the reef. It's not uncommon for them to retreat to fissures and other difficult to reach areas when threatened, waiting until the coast is clear. These fish are also associated with ledges which they hide under while swimming upside down! They live from shallow tidal areas to water up to 200 feet (60 m) deep. Grammas live in the West Atlantic Ocean throughout the Caribbean, the Gulf of Mexico, and the northern South American coast. Lionfish are an invasive, introduced species in this part of the world, and these unwelcome guests dine on many native fish species including the grammas! This non-native predator, along with the aquarium trade threaten this group’s population.

Grammas form small shoals with a larger dominant fish. They usually work together to protect a foraging area where they may remain for months if they're not driven out. Grammas are helpful reef fish because they clean up other species around them. These fish eat parasites from the bodies of other fish. Did you know fish can have ectoparasites? They can even have “lice!” Grammas also eat planktonic crustaceans. Typically, the adults of the group have the best opportunities for getting food and avoiding predators with juveniles often being pushed to the edges of the group.

In grammas, their sex only becomes apparent when they reach adult size, prior to this they have features of both sexes. Males have multiple partners and take care of their eggs in an algae lined nest, often located in a small cave or rock crevice. Contrary to what some sources indicate, grammas do not brood their offspring in their mouth. Females enter the male's brooding chamber and lay their eggs inside. Most commonly, these fish lay their eggs at night. They're also laid in the nest asynchronously, with different females arriving at different times to lay their eggs, so the eggs hatch at different times as well! Each female lays around 20 to 40 eggs and these hatch after about two weeks. The fry also have big eyes and well developed jaws, so they're ready to hunt from birth!

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