Stegastes
Genus of fishes
title: "Stegastes" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["stegastes", "pomacentrinae", "marine-fish-genera", "taxa-named-by-leonard-jenyns"] description: "Genus of fishes" topic_path: "general/stegastes" source: "https://en.wikipedia.org/wiki/Stegastes" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Genus of fishes ::
| image = Stegastes lacrymatus, simons two mile sodwana imported from iNaturalist photo 148477328.jpg | image_caption = Stegastes lacrymatus | taxon = Stegastes | authority = Jenyns, 1840 | type_species = Stegastes imbricatus | type_species_authority = Jenyns, 1840 | synonyms = *Brachypomacentrus Bleeker, 1877
- Eupomacentrus Bleeker, 1877 ::figure[src="https://upload.wikimedia.org/wikipedia/commons/2/24/Caribbean_Cocoa_damselfish.jpg" caption="Caribbean cocoa damselfish]] (''Stegastes xanthurus'')"] ::
Stegastes, commonly known as Gregories, is a genus of ray-finned fish in the family Pomacentridae. Members of this genus are marine coastal fishes except for S. otophorus, which also occurs in brackish water. These fish are known by the names of damselfish, gregory and major. They are small tropical fish associated with coral and rocky reefs in the Atlantic, Indian and Pacific Oceans. They are sometimes found in the aquarium trade where they are an easy-to-keep fish, but they do not mix well with other fish of their own or other species because of their territorial habits and aggressiveness.
Description
The largest species in the genus is S. acapulcoensis, which grows to a maximum length of 17 cm, while the smallest is S. pictus at 7.5 cm. Members of this genus are deep-bodied and laterally flattened fish with forked tails. The head has a blunt snout, a small, terminal mouth, a nostril on each side of the face, and large eyes. The lateral line does not run the full length of the body and has gaps in it. A single large dorsal fin is present and the anal fin has two, or rarely three, spines. The colour varies with the species and sometimes varies in different parts of the fish's range. Juvenile fish tend to have bright colours which are completely different from the appearance of adults of that species. The brown color of Stegastes apicalis was shown to arise from melanosomes containing pheomelanin unlike most fish species's melanosomes that contain eumelanin.
Behaviour
These damselfish feed on filamentous algae which make up about 90% of their diet, although they may consume detritus and some invertebrate material, possibly ingesting it accidentally with the algae. They are territorial and cultivate the algae, guarding their garden from other fish. Most species of Stegastes live a solitary existence, though some live in association with a member of the opposite sex and a few form loose aggregations of a small number of individuals. They tend not to face too much competition from other fish because of the very shallow water in which they live and because their habitat is not actually on reefs, but is near them, among boulders, dead branching corals, man-made structures, and junk. Most species are very aggressive and attack anything that moves into their territory, including nipping divers to drive them away.
Their behaviour changes somewhat during the breeding season. The male prepares a nesting site by cleaning a smooth piece of rock, removing algae and debris, and removing or driving away from the vicinity unwanted invertebrates such as starfish and sea urchins. He then signals his readiness to breed by changing hue and displaying his brighter colours. A female that accepts his advances lays a single layer of eggs which she attaches to the prepared rock. The male fertilises them and then stays to guard them, removing any debris that lands on them or unfertilised eggs and fanning the developing embryos with his fins to keep them well oxygenated. The eggs hatch in about a week, the larvae drifting away as part of the plankton. About a month later, they settle to the seabed and undergo metamorphosis into juveniles, well away from the territories occupied by the adults.
In the aquarium
Stegastes species may be offered to new aquarists on the grounds that they are easy to care for. They will indeed tolerate poor water quality and feed on the algae which is often a nuisance in reef tanks, but because of their aggressive behaviour, they should not be kept with other fish, especially smaller ones.
Species
FishBase lists the following species: ::data[format=table title=""]
| Species | Common name | Adult | Juvenile |
|---|---|---|---|
| Stegastes acapulcoensis | [[File:Stegastes acapulcoensis, Carrizales imported from iNaturalist photo 134515106 (cropped).jpg | frameless]] | |
| Stegastes adustus | [[File:Stegastes adustus St Kitts & Nevis (cropped).jpg | frameless]] | |
| Stegastes albifasciatus | [[File:Stegastes albifasciatus 343581164 (cropped).jpg | frameless]] | |
| Stegastes arcifrons | [[File:Stegastes arcifrons 228148306 (cropped).jpg | frameless]] | |
| Stegastes baldwini | |||
| Stegastes beebei | [[File:Stegastes beebei 7729383 (cropped).jpg | frameless]] | |
| Stegastes diencaeus | [[File:Stegastes diencaeus, Matanzas, Cuba imported from iNaturalist photo 61245753 (cropped).jpg | frameless]] | |
| Stegastes flavilatus | beaubrummel | [[File:Stegastes flavilatus 425041809 (cropped).jpg | frameless]] |
| Stegastes fuscus | dusky damselfish | [[File:Stegastes fuscus 234718481 (cropped).jpg | frameless]] |
| Stegastes imbricatus | [[File:Stegastes imbricatus 256393418.jpg | frameless]] | |
| Stegastes lacrymatus | [[File:Stegastes lacrymatus 296753928 (cropped).jpg | frameless]] | |
| Stegastes leucorus | [[File:Stegastes leucorus.jpg | frameless]] | |
| Stegastes leucostictus | [[File:Stegastes leucostictus 450924535 (cropped).jpg | frameless]] | |
| Stegastes limbatus | [[File:Stegastes limbatus 69113424 (cropped).jpg | frameless]] | |
| Stegastes lividus | |||
| Stegastes lubbocki | |||
| Stegastes nigricans | [[File:Dusky gregory Stegastes nigricans male with courtship coloration (5847342788) (cropped).jpg | frameless]] | |
| Stegastes otophorus | freshwater gregory | ||
| Stegastes partitus | [[File:Stegastes partitus 360685555 (cropped).jpg | frameless]] | |
| Stegastes pelicieri | [[File:Stegastes pelicieri Réunion.jpg | frameless]] | |
| Stegastes pictus | [[File:Stegastes pictus 110716929 (cropped).jpg | frameless]] | |
| Stegastes planifrons | [[File:Stegastes planifrons 469407634 (cropped).jpg | frameless]] | |
| Stegastes punctatus | [[File:Stegastes punctatus 435454375 (cropped).jpg | frameless]] | |
| Stegastes rectifraenum | [[File:Stegastes rectifraenum 53801865 (cropped).jpg | frameless]] | |
| Stegastes redemptus | [[File:Stegastes redemptus (cropped).jpg | frameless]] | |
| Stegastes rocasensis | [[File:Stegastes rocasensis, Brazil imported from iNaturalist photo 171031754 (cropped).jpg | frameless]] | |
| Stegastes sanctaehelenae | |||
| Stegastes uenfi | |||
| Stegastes variabilis | cocoa damselfish | [[File:Stegastes variabilis, Bahia, BR imported from iNaturalist photo 344696060.jpg | |
| Stegastes xanthurus | [[File:Stegastes xanthurus 470241045.jpg | frameless]] | |
| :: |
References
References
- WoRMS. (2013). "''Stegastes'' Jenyns, 1840".
- "''Stegastes''".
- {{FishBase. (2012)
- "''Stegastes''". FishBase.
- "Family Pomacentridae - Damselfishes". FishBase.
- (November 2023). "Morphological and Optical Modification of Melanosomes in Fish Integuments upon Oxidation". Optics.
- (2015). "Pheomelanin in fish?". Pigment Cell Melanoma Res..
- (1998). "Herbivory by the Dusky Damselfish ''Stegastes fuscus'' (Cuvier, 1830) in a tropical rocky shore: effects on the benthic community". Journal of Experimental Marine Biology and Ecology.
- Henry C. Schultz III. "Fish Tales". Reefkeeping.
- {{FishBase genus. (2025)
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