Bluebanded Goby, Lythrypnus dalli
Bluebanded Goby, Lythrypnus dalli. Underwater photographs taken in coastal waters off Catalina Island, California, July 2019. Photographs and identification courtesy of Bob Hillis, Ivins, Utah.
The Bluebanded Goby, Lythrypnus dalli, is a member of the Goby or Gobiidae Family, that is also known as the Catalina Goby and in Mexico as gobio bonito. They were named after the malacologish William Healey Dall. Globally, there are twenty species in the genus Lythrypnus, of which six are found in Mexican waters, three in the Atlantic and three in the Pacific Ocean.
The Bluebanded Goby has a elongated robust body with a rounded head that has a fleshy crest along the top and nape and an oblique mouth. Males and females are similar brightly colored with a bright red color that grades to orange posteriorly and a pair of narrow electric blue vertical stripes in the head region and 3 to 5 similar bars on the body, that vary from fish to fish, giving them the appearance of a glowing fluorescent neon light. Their pectoral fins are transparent. They are dimorphic with males having a longer dorsal fin than the females and a suction like disc that is formed by the pelvic fins. Their anal fin has 1 spine and 11 to 16 rays, their caudal fin is short and rounded; their first dorsal fin has 6 spines and their second dorsal fin has 1 spine and 17 rays; the pectoral fins have 18 to 10 rays; and, the pelvic fins are fused to the disc. They have 5 to 7 gill rakers. They are covered with rough scales.
The Bluebanded Goby is a small demersal species found sitting on rocks in open rocky areas and in reefs or hanging upside down in underwater caves at depths up to 75 m (246 feet). They reach a maximum of 6.4 cm (2.6 inches) in length. They are microcarnivores that consume small crustaceans on the reef surface or from the water column directly above and can be seen darting in an out of holes to capture food. They utilize crypsis and retreats to crevices or holes in rock structure or they hide in the spines of the Purple Sea Urchin, Echinometra vanbrundti, for protection against predation. They seldom leave the ocean floor and have a very limited home range always remaining very close to access to a hiding location. They are one of the few animals on planet earth that have the ability bidirectionally, male to female (protandry) or visa versa female to male (protogymy). Reproduction is oviparous with spawning in pairs with female laying eggs in empty shells that attach to the shell’s wall and are then fertilized and guarded vigorously by the males until they hatch. Their larvae are pelagic. The Bluebanded 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 Bluebanded Goby is a resident of all Mexican waters of the Pacific Ocean.
The Bluebanded Goby is a straightforward identification and cannot easily be confused with any other species. They are often found associated with the Zebra Goby, Lythrypnus zebra.
From a conservation perspective the Bluebanded Goby is currently considered to be of Least Concern with stable, widely distributed populations. They are considered to play an important role to a reefs ecosystem. They are utilized extensively by the aquarium trade due to their beauty and color but require high maintenance levels with ample space and hiding locations. Being a peaceful fish, they are considered to be excellent for reef tanks. They are short lived in captivity, however, and require colder waters 20°C (68°F) to 22°C (72°F) for survival than most aquarium fishes. They are available for purchase via the internet for approximately $25.00 each.