Fire under water? The Firefish Goby is a brightly colored tropical fish with a slender body and elongated dorsal fin. Sporting vibrant shades of red, orange, and yellow, this goby resembles a flickering flame underwater, not only because of its colors, but also because it often darts quickly into the coral reefs for safety at the slightest hint of danger. The Firefish goby is also a monogamous fish!