Crazy Fish (Butis butis)

An unusual Sleeper Goby that is found along nearly every coastline of the Indo-Pacific region, the Crazy Fish or Upside Down Sleeper Goby is amphidromous, which means they regularly move between freshwater in marine habitats. Their name reflects their habit of swimming upside down or at an angle, normal behavior for this species. Although they are sometimes marketed as a freshwater fish (and can be kept as such as juveniles), they will do best in light to moderate strength brackish water. Typically found in estuaries and mangrove forests, these fish are active and fast-moving predators that feed on small fish and invertebrates in the wild but are peaceful toward any tankmates too large to be eaten.