Colon Goby, Coryphopterus dicrus
Colon Goby, Coryphopterus dicrus. Fish caught within the Indian River Lagoon, Micco, Florida, May 2021. Length: 5.0 cm (2.0 inches). Catch, photograph and identification courtesy of Ben Cantrell, Sebastian, Florida.
Colon Goby, Coryphopterus dicrus. Fish caught from a freshwater drainage system in Sebastian, Florida, December 2022. Length: 5.1 cm (2.0 inches). Catch, photograph and identification courtesy of Ben Cantrell, Sebastian, Florida.
The Colon Goby, Coryphopterus dicrus, is a member of the Goby or Gobiidae Family, that is also known as the Colon-sand Goby and is known in Mexico as gobio dos puntos. Globally, there are sixteen species in the genus Coryphopterus of which eight are found in Mexican waters, seven in the Atlantic and this species in the Pacific Ocean. They are scientifically interesting as their larval stage is believed to be longer than their post-settlement lifespan.
The Colon Goby has an elongated body with a straight head profile with a small horizontal mouth. They are translucent gray color with numerous pink, tan or yellow spots of varying size on the sides. They have dark radiating line from the eyes, a dark bar below the eyes, a dark spot immediately behind the eye; 10 to 11 dark spots on the midline. The caudal peduncle has a dark bar joining two spots; the pectoral fin base has two dark spots; the pectoral and pectoral fins are a uniform color but have small spots on the membranes. Their anal fin has 1 spine and 9 or 10 rays; their caudal fin is rounded; their first dorsal fin has 6 spines; their second dorsal fin has 1 spine 9 rays; their pectoral fins have 18 to 20 rays; and, their pelvic fins have 1 spine and 5 rays and are fused into a sucking disc. Their body is covered with large rough scales. They do not have a lateral line.
The Colon Goby is found as solitary individuals within coral and rocky reef environments adjacent to white sand at depths up to 15 m (38 feet). They reach a maximum of 5.0 cm (2.0 inches) in length. They feed primarily on benthic invertebrates. Reproduction occurs as sequential protogynous hermaphrodites with each female depositing between 500 to 1,100 eggs on hard substrate and then fertilized by the males. They have very short life-spans. The Colon 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 Colon Goby is a resident of all Mexican waters of the Atlantic Ocean ranging from Tuxpan, Vera Cruz, along the northern Yucatán, south to the Belize border.
The Colon Goby can be easily confused with the Bartail Goby, Coryphopterus thrix (prominent black spot at the pectoral fin base), the Bridled Goby, Coryphopterus glaucofraenum (dark spot on top of the caudal peduncle), the Crested Goby, Lophogobius cyprinoides (large black and orange blotch at the front of the first dorsal fin), the Goldspot Goby, Gnatholepis thompsoni (small gold ocellus over pectoral base), the Pallid Sand-goby, Coryphopterus eidolon (yellow-orange lines and spots) and the Sand Goby, Coryphopterus tortugae (dark triangle over the gill covers).
From a conservation perspective the Colon Goby is currently considered to be of Least Concern with stable, widely distributed populations. They are small in stature and are of little interest to most. They are known to be preyed upon by the newly introduced highly invasive Red Lionfish, Pterois volitans. Their long term viability is threatened by habitat deterioration and related coral loss and their population levels have been in significant decline over the last 50-years.