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Chromis cyanea, Blue Chromis. Scott W. Michael

Family: Pomacentridae

Species in Genus Chromis:

Reference: A PocketExpert Guide to Reef Aquarium Fishes
Image credit: SWM
Text credit: SWM


This is the largest damselfish genus with over 80 species—all great for the reef aquarium, as chromises are mild-mannered with other fishes and never a threat to ornamental invertebrates.

In the wild, many form large shoals that swim above the reef to capture passing zooplankton in the water column. It is possible to keep them in groups in a moderate-sized tank (e.g., 70 gal. [266 L]). They will form a dominance hierarchy, with subordinate members often receiving an unequal share of mistreatment from their conspecifics. If the group is large enough, the aggression will be spread out so that no one fish gets too much abuse. They spend most of their time in the open and in the upper layers of the aquarium and can act as dither fishes.

Chromises tend to be less durable than some other damselfishes, are more susceptible to disease, and are more likely to be abused by aggressive tankmates. Some can be quite nervous, dashing about the aquarium or hiding most of the time. They tend to lose their vibrant colors if not fed a color-enhancing food. Juveniles tend to acclimate more readily than adults.