Engineer Goby - Pholidichthys leucotaenia - Small Juvenile

Even though these fish are called Engineer Gobies and Convict Blennies, they aren't actually gobies or blennies at all. They belong to another family of fish, the family Pholidichthyidae. They are the only fish in this family and are sometimes confused with other gobies, blennies and even eels.

Young Engineer Gobies look very different from adults. Juvenile Engineer Gobies are black with white horizontal stripes to mimic another fish known as the Coral Catfish (Plotosus lineatus) in their behavior and coloration. This helps them to defend themselves against other fish because, while the Engineer Gobies are harmless, the Coral Catfish is venomous. They will often hover in the water or around ledges in big groups to look like one big fish instead of lots of little ones. Adult Engineer Gobies have thick vertical bars like their other name, the Convict Blenny, suggests and are much more secretive as they grow older. Adults are usually found in their tunnels and burrows. They even lay eggs and raise their young in these tunnels.

Engineer Gobies are generally very hardy. They aren't usually found swimming around like many other fish. Instead, they build tunnels and burrows around the rockwork. In some aquariums and on the coral reefs where these fish live, their tunnel-building habits have even caused the rockwork over them to collapse! Engineer gobies will eat just about any kind of food, from frozen to flake, even small fish on rare occasions. They are a social fish and do best in groups of 3 or more, as long as the aquarium is suitably large.