The Yellowfin goatfish (Mulloidychtys vanicolensis) is also known as the Golden banded goatfish and the Goldstripe goatfish. They are not common in Tanzanian coastal waters and are only occasionally seen. Their habits differ from those of most other goatfish in that they are nocturnal feeders and form large shoals during the day. Goatfish all have a pair of retractable barbels or feelers that have sensory organs in them to detect prey. They all have proportionally long bodies with a deeply forked tail.
The Yellowfin Goatfish has a slightly more streamlined shape compared to most Goatfish. The upper body and dorsal and caudal fins are a bright yellow gold color. The lower body is silver grey in color and there is a bright gold horizontal stripe across the mid body. The scales just above and below the stripe are lightly flecked in blue. The anal and pelvic fins are yellow. They grow up to 38 cm in length.
Most Goatfish have color change abilities and this species is no exception, at night feeding they drop the yellow color as pictured above and have the ability to go red as pictured below.
The above images are of the same specimen which has adjusted its color in a matter of seconds once the lights have gone on it.
The Yellowfin goatfish is found across the Indo Western Pacific Ocean. They are found from East Africa across to Australia and north to Japan. They are also found in Hawaii and French Polynesia.
The Yellowfin goatfish feed on worms and small crustaceans. During the day they swim above the reef, however at night the descend onto the substrate to hunt for food. Once they begin searching an area the comb it quite meticulously with their barbels. The barbels are quite prehensile and they have a large degree of control over them. Both seem to operate independently and if they allow one to get close while feeding, it is quite interesting to watch them.
Little is known of their breeding habits but their eggs are released into the substrate and they have a long larval period. Once the barbels begin forming they become benthic.
Yellowfin Goatfish are not commonly kept in aquariums and their potential size of 38 cm they would require a large tank with large tank mates as a prerequisite. Because of their tendency to root around they are not suitable for reef tanks and rocks would have to be be well anchored.