Damselfish
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Damselfish are lively and colorful members of the coral reef community. Found in all tropical seas, they are known as demoiselles in the Mediterranean region. More than 200 species of brightly colored damselfish can be found in the shallow waters of both tropical and semitropical seas. Even though these fish are small, they are extremely aggressive and vigorously defend their territory against competitive species and sometimes even against human divers.

Habits: Damselfish are found in all tropical and some semitropical seas, and certain species inhabit fresh or brackish water. Damselfish are most abundant in the Indo-Pacific region. They usually live in shallow water around coral reefs, mangroves, and beds of sea grass. Some species like the bicolor damselfish occur at depths of over 250 feet. Juveniles of some species like the night major are common in tropical tide pools, while the yellow-orange garibaldi is found in more temperate regions. It feeds on small animals in the seaweed that grows in beds off the coast of California. Tube like coral formations provide sleeping places for damselfish. Some species form schools a spectacular sight against the reef.

Behavior: Damselfish are known for their ferocious and territorial behavior. Certain bottom dwelling species like the three spot damselfish can defend a territory up to 16 feet across. The territory usually includes feeding and spawning sites and a shelter for protection from predators. A damselfish defends its territory against fish that compete for similar environments, such as butterfly fish and surgeon fish, even if they are much larger. But it generally ignores less competitive species like bass and groupers. Some other damselfish are less territorial and live in open water in schools ranging from six to several hundred fish. Damselfish stay close to the coral reef, often darting into dark crevices to hide from predators. Some species remain in the same colony for two years.

Food and Feeding: Some damselfish feed on zooplankton (tiny waterborne crustaceans and fish larvae) as they hover above coral reef formations. Many others graze on the seabed, eating algae (primitive plants) and small bottom dwelling invertebrates such as shrimp and crabs. The three spot damselfish and certain other species cultivate algal lawns thick patches of algae. They eat the algae along with the invertebrates that colonize the lawn. These lawns also provide sites for organisms that attack and destroy coral, changing the composition of the surrounding coral reef community in the process. Some species of damselfish feed on algae that grow on the seabed. Invertebrates such as shrimp and crabs that also feed on the algae provide another valuable source of food.

Breeding: After establishing a territory, a male damselfish cleans a rocky ledge or coral surface to prepare it for spawning. Using color changes, excited swimming movements, and, in certain species, clicking sounds, the male fish encourages a mature female to approach the spawning site and lay her eggs, which he quickly fertilizes. Courtship and mating take about 10 to 20 minutes. Some males may mate with several females.

Each female fish lays up to 20,000 tiny oval eggs, which the male tirelessly guards and tends. He fans water across the eggs with his fins, sometimes picking out dead eggs that could threaten the whole batch. Male damselfish defend their eggs against fish much larger than themselves with little regard for their own safety. The eggs hatch after three to seven days, and the larvae spend weeks drifting and feeding on animal and plant plankton. Some species of damselfish mature at two or three years of age while others take much longer. During courtship rituals vibrant colors distinguish the sexes more clearly.

Key Facts:
Size:
Length: Up to 14 in. but usually smaller

Breeding:
Sexual maturity: 2-5 years
Spawning season: Spring to summer in temperate regions; less seasonal in the tropics.
No. of eggs: Up to 20,000
Hatching time: 3-7 days

Lifestyle:
Habitat: Territorial. Some species form large schools
Diet: Plankton, bottom living invertebrates, algae
Lifespan: Up to 18 years in captivity. Less in the wild

Related Species: There are 235 species within the damselfish family, including 26 species of clownfish.
Distribution: Found in tropical and some semitropical seas extending into fresh and brackish water in some areas.
Conservation: Damselfish are popular aquarium fish, but collection does not seem to be a threat so far. Habitat destruction and pollution are problems facing all aquatic habitats, and coral reefs are especially vulnerable.

Different Species of Damselfish:
Blue damselfish, Pomacentrus caeraleus: The young live together peacefully but become more aggressive as adults.
Black and white damselfish, Dascyllus aruanusa: also known as the humbug fish. Extremely territorial.
Young beau-gregory damselfish, Eupomacenteus leucostictus: Found only in the Caribbean.
Yellow damselfish, Microspathodon chrysurus: Damselfish like this often lose their bright colors in captivity as they adjust to their new surroundings.

Did You Know:
Damselfish make unusual purring or clicking noises that are used in courtship.
The same noises are used to warn off intruders.
Juvenile damselfish may be a different color than mature fish.
The young garibaldi is red with blue spots and fin edges. When it matures, it becomes a startling yellow-orange color.
The young of one species, Acanthochromis polyuacanthus, feed on mucus secreted by their parents skin.