The descriptively named two-tone chromis is found in the Indian Ocean, and was only recently identified as a separate species from the similar Chromis dimidiata (which is found exclusively in the Red Sea). It is resident on lagoon and seaward reefs up to 40 metres deep, and is easily
identified thanks to the striking half dark brown, half white markings that give it its name. Two-tone chromis avoid areas of heavy wave action and grow up to nine centimetres in length. Like other chromis species, it forms distinct pairs during breeding season. The female lays a clutch of adhesive eggs that stick to the substrate, while the male is responsible for aerating the eggs and guarding them from would be predators.
The blue-spotted chromis is found in the Western Indian Ocean, from Delagoa Bay in Mozambique to just south of Durban, South Africa. Despite its small distribution, the blue-spotted chromis is
considered abundant within its range and favours rocky reefs up to 15 metres deep. It is usually seen in small shoals, swimming directly above the reef. Blue-spotted chromis reach lengths of up to 12 centimetres, and have a blue-grey body with yellow patches on the forehead and upper flanks. They feed on zooplankton and are oviparous, which means that they lay eggs. These eggs are the result of distinct pairing during breeding season, and are adhesive so that they don’t wash away. Male blue-spotted chromis guard and aerate the eggs.
The Weber’s chromis is found throughout the Indo-Pacific, from the Red Sea and the eastern coast of Africa to southern Japan and New Caledonia. It is a non-migratory resident of reefs up to 40 metres deep, and
favours passes, channels and steep reef walls. These slender fish can be spotted singly, or in groups that can become quite large. They are blue in overall colour, with iridescent green scales on their flanks and tails outlined in black. There is also a small black mark where the pectoral fins join the body. Weber’s chromis grow up to 13.5 centimetres in length, and form pairs during breeding season. As is common for this genus of fish, the female lays adhesive eggs that stick to the seafloor, while the males guard them and keep them aerated.
Also known as the domino damsel or threespot dascyllus, the domino is found throughout the Indo-Pacific from East Africa and the Red Sea to southern Japan and Australia. It prefers rocky and coral reefs up to 55 metres deep, and is most often found in groups.
The domino has a greyish black body with a white spot on the forehead and one on either flank. Its colouration can vary from region to region, as can the size of its spots. Sometimes, the forehead spot isn’t visible at all, making identification difficult. Dominos pair up during breeding season and lay adhesive eggs, which the male guards and aerates to promote incubation. Upon hatching, juvenile dominos seek the protection of sea anemones, urchins and coral heads.
Found throughout the Indian Ocean from eastern Africa to Sri Lanka and the Maldives, the blacktail chromis is a small tropical species that favours areas of rich coral cover. It is thought to exclusively inhabit depths of less than 30 metres, and is a resident species on the reef.
Blacktail chromis reach a maximum length of six centimetres, and usually live in small shoals. They are an attractive species with a large silver eye and a dusky oval-shaped body complete with horizontal yellow stripes on the lower half. Their anal fin is blue, their dorsal fin is tipped with blue, and ironically, their tail fin is yellow, not black. Blacktail chromis form distinct pairs during breeding season. They produce adhesive eggs, which the male fish guards and aerates to ensure successful incubation.
Also known as the caerulean damsel or the blue-yellow damsel, the blue pete is easily recognisable by its electric blue colouring. The species has a solid band of yellow on the lower half of its body; and yellow pectoral, anal and tail fins. Blue petes are found throughout the
Western Indian Ocean, from eastern Africa to the Maldives. Aliwal Shoal represents the southern boundary of its range in South Africa, and there is an anomalous record of the species from Bali in Indonesia. Blue petes favour lagoon and sloping outer reefs, and generally prefer areas with plenty of coral rubble. They reach a maximum of 10 centimetres in length, and form distinct breeding pairs in season. They lay eggs, which (like the blacktail chromis) the male guards and aerates.