''Stegastes variabilis'' (cocoa damselfish) is a
damselfish in the
family 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 and rocky reefs in the
Caribbean Sea and neighboring areas of the
Atlantic Ocean and
Gulf of Mexico. 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.
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 sponges, ascidiacea and anemones, 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 nemerteans.[ Individual Stegastes variabilis don't overlap territories with other damselfish.]
Breeding
In the breeding season, the female lays eggs 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.]
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