Chameleon Goby, Tridentiger trigonocephatus
Chameleon Goby, Tridentiger trigonocephatus. Fish caught from within Mission Bay San Diego, California, December 2022. Length: 6.2 cm (2.4 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Chameleon Goby, Tridentiger trigonocephatus. Both fish caught from within San Diego Bay, San Diego, California, January 2019. Length: 8.2 cm (3.2 inches) and 9.2 cm (3.6 inches) respectfully. Shortly after the catch the striped fish changed its coloration to match the coloration of the first fish photographed above. Catch, photograph and identification courtesy of Ben Cantrell, San Diego, California.
Chameleon Goby, Tridentiger trigonocephatus. Fish caught from coastal waters off San Diego, California, December 2020. Length: 8.2 cm (3.2 inches). Catch, photograph and identification courtesy of Ben Cantrell, San Diego, California.
The Chameleon Goby, Tridentiger trigonocephatus, is a member of the Goby or Gobiidae Family, that is also known as the Striped Triple Toothed Goby, the Toothed Goby, and the Trident Goby and in Mexico as gobio camaleón. They obtained their common name for their ability to change colors from a striped to a barred pattern and visa versa. Globally, there are nine species in the genus Tridentiger with this species being the only one found in Mexican waters of the Pacific Ocean.
The Chameleon Goby has an elongated body with a depressed head that are much broader than they are wide with a large oblique mouth. They are a pale grayish-brown color with a white-speckled head and two distinct longitudinal black stripes. The stripes are often broken by irregular vertical bands, or can be absent in larger fish. The first runs from behind the eye to the tail fin; the second from the snout along the upper portion of the pectoral fin to the tail fin. The anal fin has an orange or grey band along the middle and the 2 dorsal fins may be speckled with white and have a brown horizontal stripe. Adults have a broad yellowish bar at the base of the pectoral fin. They have the ability to darken in color so that the black bands become invisible. The anal fin has 1 spine and 10 or 11 rays and the dorsal fin has 7 spines and 12 to 14 rays.
The Chameleon Goby is a demersal species that is found in shallow freshwater, brackish with salinities in excess of 22 ppt, and marine habitats under rocks, in burrows, or in crevices and in seagrass meadows at depths up to 18 m (60 feet). They reach a maximum length of 11 cm (4.3 inches). They are nighttime predators that prey upon amphipods, crab larvae, hydrozoans and large quantities of polychaetes worms. Reproduction is oviparous with males constructing nests in hard substance which as clam and oyster shells and the eggs are deposited in the nests by the females which are then guarded by the males until they hatch in ten days. Each female can spawn up to ten times per year. They have lifespands of three years. The Chameleon Goby is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Chameleon Goby is a resident of Mexican waters of the Pacific and has been reported to be present along the northwest coast of Baja but this presence has not been documented and confirmed scientifically. They are known, including the fish caught and photographed above, to be present in San Diego Bay.
The Chameleon Goby is similar in appearance and can be confused with the Shimofuri Goby, Tridentiger bifasciatus (lacks white spots on the underside of its head; has a red-orange margin on the anal and second dorsal fins; and is found in waters with less salinity).
From a conservation perspective the Chameleon Goby has not been formally evaluated. They are a native of China, Japan, Korea and Siberia but have been introduced as juveniles and larvae in ship ballast water or via eggs laid on the hulls of intercontinental ships and can presently be found in the coastal waters of Australia, Israel and the United States and in the Black Sea. They were first recorded in Los Angeles in 1960 and in San Diego in 1995. They are considered to be a highly invasive species that will compete with native species and they have been identified as one of ten species most likely to spread to uninfected areas by shipping. The damage assessment of their presence has not yet been determined within the invaded ranges.