Longfin gregory (Stegastes diencaeus) care guide

Group
Marine fish
Other names
Longfin damselfish
Family
Pomacentridae (damselfishes)
Origin
Western Atlantic and Caribbean coral reefs (range not checked for this page).
Water
saltwater
Maximum size
12.5 cm
Temperature
24–27°C
pH
8.1–8.4
Hardness
Salinity SG 1.023–1.026
Minimum tank
150 litres
Care level
intermediate
Temperament
aggressive
Reef safe
with_caution

Care

Tank: a reef or fish-only aquarium with rockwork and caves for shelter. Tank: an estimated minimum of about 150 litres (our estimate from the adult size and habits, not a figure from the sources). Water: the sources give no species-specific figures, so the values here are general marine aquarium guidance, not species-specific: 24–27 °C, pH 8.1–8.4 and specific gravity 1.023–1.026. Keep conditions stable with good filtration and regular water changes. Behaviour: The list says it becomes highly territorial as it ages. Identification: Up to about 12.5 cm. The list notes it turns brown with age. Trade: not CITES-listed. This page is based on the Wikipedia list entry only; the species article was not checked, so range and behaviour details should be confirmed before relying on them. Sources: Wikipedia, List of marine aquarium fish species (en.wikipedia.org/wiki/Listofmarineaquariumfishspecies). Checked October 2026.

Diet

No diet details were checked for this species. As general guidance for damsels, offer a varied omnivorous diet of frozen mysis and brine shrimp, flake, small pellets and algae-based food.

Breeding

No species-specific breeding information was checked for this page. As general damselfish guidance, pairs lay sticky eggs on a hard surface the male has cleaned, and he guards and fans them until they hatch after a few days. The larvae are tiny and planktonic, so rearing needs live first foods such as rotifers.

Compatibility and tank mates

The list rates it reef safe "with caution". Gregories are known to nip at corals and keep algae patches, so watch soft corals. Highly territorial: keep with robust fish.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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