The Zanzibar Butterflyfish (Chaetodon zanzibarensis) is not that common on the coast of mainland Tanzania but is fairly common on Zanzibar and Mafia Island. They are colorful fish and are easy to spot from a distance on the reef.
From a distance it is easy to confuse them with the Yellow Teardrop Butterflyfish ( Chaetadon interuptus) pictured below. The black dot on the Yellow Teardrop Butterflyfish is as its name suggests teardrop shaped and is fairly easy to distinguish once one gets close. There are also no horizontal black lines on the body and the entire caudal fin is transparent.
The body of the Zanzibar Butterflyfish is a typical butterflyfish shape, laterally compressed and oval with a pointed nose. The main body color is yellow with lines of small black dots running horizontally across the body. There is a large black spot on the upper flank and a black horizontal bar runs through the eye. The rear of the caudal fin is a translucent colour. They have a pointed snout with sharp, narrow teeth and grow to up to 12 cm in length. It is impossible to sex them from their looks.
ZANZIBAR BUTTERFLYFISH IN THE WILD
Zanzibar Butterflyfish are more often than not seen singularly but they are seen in pairs. They are usually found from 10 meters downwards to 20 meters. Usually they are seen in areas with abundant acropora corals. They are fairly shy fish and are not that easy to get close to. Usually they will swim off if they feel a diver is following them. They will usually make short fast darts at the acropora corals, biting off the polyps and move off onto another formation once they have tried their luck.
Zanzibar Butterflyfish are found from South Africa north to Somalia and across to the Chagos Islands, Seychelles, Reunion, Mauritius Comoros and Madagascar. They are usually found from 10 to 20 meters in depth in Tanzanian waters.
Zanzibar Butterflyfish feed exclusively on coral polyps, mainly from the acropora species of coral.
Little is known about the mating habits of the Zanzibar Butterflyfish. As they are often seen in pairs it is assumed that they form monogamous pairs and keep the same mates, although they will find a new mate if one dies. The female swells with eggs and spawning takes place by scattering into the water table with the male fertilizing the eggs.
The eggs are spherical and buoyant and it is thought they hatch in 28 to 30 hours. Once the eggs hatch a bony plate forms over the head area and the larvae called tholichthys, are pelagic for quite some time. They slowly develop into juveniles. This phase makes it extremely difficult to breed butterflyfish in aquariums.
Zanzibar Butterflyfish are not commonly kept in aquariums because of the difficulty in getting them onto prepared foods. Some specimens may switch across and others may not and only highly experienced aquarists should attempt to keep them.