Chromis fish belong to the family Pomacentridae. They are specifically a genus of damselfish. Like all damselfish, chromis are strictly a saltwater species. Chromis originated from the Indo-Pacific Ocean and can be found near places sure as the Solomon Islands, Papua New Guinea, Thailand and the Philippines. Some species have also been observed in the Atlantic near places such as Hawaii, Honduras and the Mediterranean Sea. Chromis are very reef-based with their territory and can commonly be spotted near coral such as Acropora. Damselfish are recognizable by their slim oval bodies and forked tails. They have a single nostril on each side of their head, and interrupted lateral lines. Chromis portray a variety of bright colorations. Damselfish are generally omnivorous, though some species may consume more zookplankton and phytoplankton than others. Algae will also make up a big part of their diet. Damselfish themselves are usually known for being very territorial and aggressive, but some chromis species like blue-green chromis are much more subdued in nature.
Chromis prefer to be a part of a shoal or school of fish in groups of anywhere between 6 and 20 chromis in the wild. They do have a social hierarchy with one male and several females. Chromis are oviparous, so the females will lay their eggs in the nest built by the male where he fertilizes them. A male will eat any unfertilized eggs to prevent bacterial and fungal infections from spreading among the whole spawn. The male will then guard the eggs and use his caudal fin to fan freshwater over them. Chromis are a popular choice for an aquarium fish because they are fairly disease resistant, colorful and less aggressive than other damselfish. Aquarists are recommended to start with at least six chromis because of their schooling nature. Chromis don’t appear to hold an endangered status. Even with collection and transportation for the aquarium trade, more efforts are being made to culture popular species such as the green chromis. This helps to ensure the wild populations don’t get overexploited.