Pseudotropheus sp. "acei" (also known as yellow-tail acei) is a Mbuna cichlid from Lake Malawi that grows to around 7 in (18 cm) in length. Although known for many years, it has not been formally described. There are two different varieties: The most common yellow-tailed Pseudotropheus sp. "acei" (Msuli), and the white-tailed Pseudotropheus sp. "acei" (Ngara). Like most Mbuna, it dwells in shallower waters, however it will sometimes go near the surface, which is very uncommon for Mbunas. It is a very common fish for fish-keepers. It gets its common name from its blue body and yellow tail. Originally discovered in 1922 by Regan, the acei was originally believe to be a Pseudotropheus, but was later changed to Gephyrochromis and then back again. It prefers the sandy and rock filled shoreline