Julidochromis marlieri is the 2nd largest species growing up to 5 inches in length. This little submarine of a fish somewhat resembles a reef fish darting in and out of coral. It will often swim upside down under rocks and dart in and out of crevices. A 20 gallon aquarium would be a good size for a single pair with a few other inhabitants. They can be extremely aggressive towards others of their own species, so it is not recommended to have multiple pairs in the same tank unless it is 50 gallons or more. The Gombe variety of marlieri is very popular among hobbyists.