Dusky damselfish facts for kids
Quick facts for kids Dusky damselfish |
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| Stegastes fuscus | |
| Conservation status | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Family: | Pomacentridae |
| Genus: | Stegastes |
| Species: |
S. fuscus
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| Binomial name | |
| Stegastes fuscus (Cuvier, 1830)
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| Synonyms | |
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The dusky damselfish (Stegastes fuscus) is a small, colorful fish. It belongs to the family of Pomacentridae, which includes many types of damselfish. You can find this fish living near the ocean floor in shallow waters. It mostly lives along the western edge of the Atlantic Ocean.
What It Looks Like
Adult dusky damselfish can be brownish-olive or dark grey. They have thin, darker stripes running up and down their bodies. Their fins are quite large. Sometimes, the edges of their top (dorsal) and bottom (anal) fins have a blue rim.
The dorsal fin has 12 stiff spines and 15 to 16 soft rays. The anal fin has two spines and 13 to 14 soft rays. This fish can grow up to 15 cm (5.9 in) long. However, 10 cm (3.9 in) is a more common size.
Young dusky damselfish look different. They are pearly grey with blue spots on their heads. They have a big, black spot with a blue rim near their dorsal fin. Another smaller, similar spot is found near their tail. Some young fish off Brazil have bright yellow and orange on their backs and dorsal fins.
Where It Lives
Stegastes fuscus lives in shallow waters off the coast of Brazil. It is very common there. You can find it on both rocky areas and coral reefs. It lives at depths down to 40 m (130 ft).
This fish has also been reported in the Caribbean Sea. However, some of these sightings might have been another similar fish. There are also reports of it near Senegal, but these need to be confirmed.
What It Eats
The dusky damselfish mostly eats algae. About 70% of its diet is algae, especially red, stringy types. It also eats some hard, chalky algae. The rest of its food comes from small invertebrates.
By eating algae, these damselfish help keep the seabed healthy. They stop larger seaweeds from taking over. This greatly affects what other plants and animals can live on the ocean floor.
How It Behaves
The dusky damselfish is very protective of its home. It guards a part of the seabed. It will chase away other fish that come too close. Sometimes, it even chases fish much bigger than itself!
The more good algae a spot has, the more aggressive the damselfish becomes. It often chases away parrotfish and bluehead wrasse. It also chases other damselfish and ocean surgeonfish.
However, some fish are not chased away. These include the smooth trunkfish and the graysby. Scientists think this is because these fish do not eat algae. They eat small invertebrates instead. So, the damselfish does not see them as a threat to its food. It's also possible these fish help the damselfish in other ways. Maybe they protect it from predators or remove tiny creatures that eat the algae.
