A damselfish is part of the Pomacentridae family of tropical fish. They usually live in coral reefs in tropical waters and are a popular choice for saltwater aquariums. Generally, the fish are small, rarely exceeding 3 inches (7.6 cm) in length. Many people enjoy the fish because of their brightly colored scales. Depending on the species, they can be blue, violet, green, brown, or red in color.
A hardy marine fish, the damselfish can typically be kept in an aquarium for more than ten years. Unlike some saltwater species, where aquarium chemistry must be kept a specific pH and temperature, these fish can survive in less than perfect water conditions. In an aquarium, most will eat dried fish food or even frozen fish food. Ideally, they should be fed a small amount of food several times each day. In the wild, they will eat small plankton, brine shrimp, and other small marine life.
Although young damselfish may congregate in small groups, as they age, they become increasingly aggressive. They can be territorial and prefer to have a specific rocky hiding place. If enough hiding places are available in an aquarium, it may help lessen the aggressive nature of the fish. Typically, the species that are blue in color are less aggressive than species of other colors.
In the wild, damselfish are considered substrate spawners. In other words, they lay their eggs on substrate, such as a rock ledge or a piece of coral. The male damselfish will stake his territory and then prepare the ledge for eggs. Next, he will attempt to attract a female to the ledge to lay her eggs by changing colors, swimming erratically, or even making subtle underwater noises. Most females are capable of laying about 20,000 eggs to a single surface while the male fertilizes them.
If an egg is dead or has a fungus, the male damselfish will typically eat it. He will also fight other fish to protect the eggs. In three days to one week, the eggs will hatch as plankton. The plankton feeds on phytoplankton and zooplankton for several weeks. It takes several years for a damselfish to mature, although the time frame varies from species to species.
Although they are easy to breed, many people worry that their natural habitat, such as tropical reefs, are in danger. Environmental groups are attempting to better protect the reefs to allow future generations of snorklers and scuba divers to see the reef fish in their natural environment.