''Stegastes variabilis'' (cocoa damselfish) is a

damselfish Damselfish are those within the subfamilies Abudefdufinae, Chrominae, Lepidozyginae, Pomacentrinae, and Stegastenae within the family Pomacentridae. Most species within this group are relatively small, with the largest species being about 30 ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Pomacentridae Pomacentridae is a family of ray-finned fish, comprising the damselfishes and clownfishes. This family were formerly placed in the order Perciformes but are now regarded as being ''incertae sedis'' in the subseries Ovalentaria in the clade Perco ...

, found on

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

and rocky reefs in the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

and neighboring areas of the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

and

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

. They are often solitary fish.

Description

The cocoa damselfish is an oval, laterally compressed fish and grows to about long. The top of the head and the snout bear several blue stripes. The top half of the body is generally dark blue or brown and the bottom half is yellow. The sides are finely barred with vertical dark lines. There are two small black spots, one above the pectoral fins and the other on the top of the caudal peduncle. The large dorsal fin has 12 spines and 14 to 17 soft rays. The anal fin has two spines and 12 to 15 soft rays. The caudal fin is shallowly forked and has rounded lobes.Stegastes variabilis
on

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

Juveniles have a number of tiny blue spots and stripes on the head and upper part of the body, including two spots and a stripe on the upper iris. These regions also have a dusky blue sheen. A blue-rimmed black eyespot is located where the dorsal fin spines join with the soft rays. A similar blue-rimmed spot is found at the top of the caudle peduncle, and it extends down nearly as far as the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

. Older juveniles develop the characteristic blue and yellow coloration of the adult.Pomacentridae: ''Stegastes variabilis''
Larvae of coral reef fishes. Retrieved 2011-12-28.

Distribution

Cocoa damselfish are found in the western Atlantic by Brazil and the Caribbean. The populations from Brazil and the Caribbean are genetically very distinct. They are also found in Florida and the Gulf of Mexico. They are marine and reef-associated. They do not migrate and have a depth range of 0 to 30 m. It is common on offshore reefs, oil platforms, and wrecks. The juveniles can occasionally appear inshore.

Ecology

Adults feed mainly on

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

but also on

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

ascidiacea Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic" ...

and

anemone ''Anemone'' () is a genus of flowering plants in the buttercup family Ranunculaceae. Plants of the genus are commonly called windflowers. They are native to the temperate and subtropical regions of all continents except Australia, New Zealand an ...

s, while juveniles feed on invertebrates such as harpacticoid

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s and

nemertea Nemertea is a phylum of animals also known as ribbon worms or proboscis worms, consisting of 1300 known species. Most ribbon worms are very slim, usually only a few millimeters wide, although a few have relatively short but wide bodies. Many h ...

ns. Individual Stegastes variabilis don't overlap territories with other damselfish. They appear to survive longer in captivity, up to 18 years, whereas they do not live beyond 12 years in the wild.

Breeding

In the breeding season, the female lays

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

on the seabed where they are attached to empty shells, stones or other objects and fertilized by the male. He then guards them, aerates them and chases away intruders. The males do this for seven days. They are aggressive when breeding. Also there is distinct pairing during breeding. Most of the communication between this species is done during breeding season.

Importance to humans

They are used as commercial aquarium fish because of their size and colorfulness.

Etymology

Stegastes is Greek for stegastos, which means covered.

References

External links

Cocoa damselfish
on ''Rock and Wreck Fishes of North Carolina''
ITIS page
* {{Taxonbar, from=Q3752068 variabilis Fish described in 1855 Fish of the Atlantic Ocean