Serranus tigrinus. The Harlequin Bass is an unusual striking yellow and black mottled mottled color on the ventral side, with black and white mottling on the dorsal half. These fishes are extremely hardy, and make a great candidate for beginners. A 75 gallon or larger aquarium with abundant hiding places provides a good environment. As the Harlequin Bass matures and grows, it may prey on any smaller fish or small crustacean tank mates. Although these fishes can boss around some smaller tank mates, they are not normally overly aggressive to dissimilar species. They do not normally take kindly to other Dwarf Sea Basses or even bottom dwelling fishes that occupy the same territory, so keep a close eye on them when mixing similar fishes or ones that occupy the same territory. Ideally only one Harlequin Bass per tank is recommended, unless a bonded pair can be obtained. A sturdy species, the Harlequin Bass requires a diet consisting of a variety of chopped live meaty items and frozen foods.