The Yellow Teardrop Butterflyfish ( Chaetadon interuptus) is not common in Tanzanian coastal waters, but neither is it rare. They obtain their name from their background color and the teardrop shape on the side of the body.
The body is laterally compressed and disc shaped as with all the Butterflyfish. The body is a bright yellow color with light chevron shaped lines running down the body. In the mid upper body there is a teardrop shaped marking. In the small juveniles there is a white ring around the mark which is rounder and not teardrop shaped. This can be seen in the image below. There is often a blue tint to the mark which dissapears as the fish ages.With the more mid sized fish as pictured above, the white outer marking goes yellow and the mark begins changing into a teardrop shape.
There is a black vertical line through the eye and a further black mark with a white edge along the rear of the dorsal and anal fins which runs across the caudal area. They grow up to 20 cm but are usually around the 15 to 17cm mark.
YELLOW TEARDROP BUTTERFLYFISH IN THE WILD
The Yellow Teardrop Butterflyfish is often seen in small groups of five to six fishes. They move across the reef feeding but usually stick low on the bottom and are quick to move into cover. They are nearly always in pairs and it is seldom that they are seen singularly. Sometimes they appear to follow groups of juvenile Parrotfish and Goatfish feeding on the reef, but they never stay with these feeding groups for long.
Their range extends from Port Alfred in the Eastern Cape Province of South Africa northwards to Somalia and across to Sri Lanka. They are absent from the Red Sea and north western Indian Ocean. Areas rich in corals on semi exposed seaward reefs seem to be their favourite spots. In Tanzanian coastal waters they are usually seen in depths of 10 to 20 meters on reef tops.
Yellow Teardrop Butterflyfish feed on hard and soft coral polyps as well as sponges, worms and various algae.
Yellow Teardrop Butterflyfish 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.
Spawning is thought to take place in relation to the lunar cycles but this is not certain. 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 them in aquariums.
Because of their penchant for coral polyps and sponges, the Yellow Teardrop Butterflyfish does not do well in aquariums. It is extremely difficult to replicate this diet in aquariums.