Chameleon Goby
(Tridentiger trigonocephalus)

Description: The chameleon goby is named for its ability to rapidly switch between a light and dark form. When in the light form, it bears two horizontal stripes that run the length of the body, one towards the top and one along the middle of the body. The dark form exhibits vertical bars that give the fish a mottled appearance. In this form, the horizontal stripes are only faintly visible, outlined by a thin row of yellow scales. Diagnostic dark bars, which are visible in both forms, are located at the base of the pectoral fin and on the area just before the tail. A yellow area, which is very conspicuous when the fish is in the dark form, follows the bar at the pectoral fin. Adults can grow to be 110 mm in length.

Habitat: This goby is typically found in the shallow waters and tidal mud flats of bays, especially in areas that contain hard substrata (shellfish beds, old bottles) favored for spawning.

Origin: Japan, Korea, eastern China, and southeast Russia.

Invaded Areas: San Francisco Bay and Los Angeles Harbor; Australia.

Concerns: Chameleon gobies are aggressive and voracious predators of crustaceans, polychaetes, gastropods and fish eggs. Capable of feeding in total darkness and tolerant of wide ranges of salinity, temperature, and pollution, they may be able to outcompete native predators, including other gobies. They have a long reproductive period, aggressive tactics for procuring spawning sites, a short development time, and male nest-guarding, all of which can contribute to rapid population growth under favorable conditions.