Blue Chromis ( Chromis Cyanea) is a bright blue, shallow water fish found in many coral reefs throughout the Caribbean. It is a small fish with an average length of 13-15 cm and also can be found in brown color (see Brown Chromis). It is found in many reefs in the North Coast of Dominican Republic, including the snorkeling spots of Sosua Beach.
Blue Chromis have an oval-shaped body, with a continuous dorsal fin and small mouth. It has a distinct, deeply forked tail. Their iridescent blue color contrasts with the black dorsal stripe and black margins of the dorsal fin. Males may exhibit one of five color morphs, including dark-grey blue and light blue shades. This is a preferred fish in aquariums, specially due to its beautiful colors.
Range & Habitat
Blue and Brown Chromis are found in the Caribbean Sea, Bermuda and Southern Florida. Normally found at depths of 3-5 meters, it can reach 25 meters below sea level and has been recorded at 60 meters. It is often found in lagoons and reef communities to feed on plankton.
The younger ones stay near the bottom to avoid predation, and adult males keep a solitary breeding territory. They prefer water temperatures of 21 to 27°C, and require healthy coral to survive. Reefs provide them with a place for breeding, feeding and protection. They prefer yellow finger coral and smooth flower coral.
Chromis feed on plankton suspended in the water column. Copepods, tunicates, shrimp larvae, siphonophores, fish eggs, and ostracods. They remain stationary and let the current bring the food to them; by quickly extending the jaw, they create negative pressure that sucks prey into the buccal cavity.
Size & Reproduction
This species is promiscuous, so many females visit many nests to lay eggs and males mate with multiple females. After breeding with multiple females, the males guard the eggs until the planktonic larvae hatch. Location and condition of the nest plays a role in the male reproductive success.
The greatest threat to Blue Chromis is the rapid expansion of the Lionfish in the Caribbean, also other tropical native fish. The loss of live corals do have a negative impact on the species, not to mention the heavy aquarium trade.