Blue devil damselfish

The blue devil damselfish (Chrysiptera cyanea) is a small marine damselfish of the family Pomacentridae, native to reefs of the western Pacific and eastern Indian Ocean. Males are an intense electric blue, often with an orange tail depending on region, while females are blue overall. Its brilliant color and hardiness make it a popular but feisty aquarium fish. It is territorial and aggressive despite its small size, defending a chosen patch of reef against much larger fish. It is best added last to a community and kept with equally robust species. A reef aquarium with abundant live rock providing crevices and territories helps disperse aggression. It is an unfussy omnivore accepting flakes, pellets, and frozen foods. Reef-safe with corals and invertebrates. Very hardy and tolerant of a range of conditions, making it easy to keep though challenging to house peacefully. It can spawn in captivity, males guarding eggs on rock.