Panamic Green Moray, Gymnothorax castaneus
The Panamic Green Moray, Gymnothorax castaneus, whose common Spanish name is morena verde panámica, is a member of the Muraenidae or Moray and Snake Moray Eels Family, known collectively as morenas in Mexico. There are one hundred sixteen global members of the Gymnothorax Genus, of which eighteen are found in Mexican waters, nine in the Atlantic and nine in the Pacific.
The Panamic Green Moray has a stout elongated compressed body that tapers gradually to a rounded tail. They vary in color with various shakes of green, greenish brown and brown and some fish have small white spots. They quickly fade to a uniform dark brown upon death. They have a large black spot covering the gill openings. The head is large with a pointed snout with small eyes, the front nostrils have tubes, the rear do not, a large mouth equipped with visible canine and smaller conical not serrated teeth with one row on the side of the top jaw and three longitudinal rows at the front. The anal fin and dorsal fins are well developed, covered with skin, and continuous with the caudal fin. The dorsal fin orginates in front of the gill openings. The tail is approximately one-half or slightly greater than 50% of the body length. They do not have pectoral fins or scales. They are covered with a thick yellow mucus that provides them with protection from abrasion.
The Panamic Green Moray are a poorly studied poorly documented species with very little known about its behavior. They are found in shallow reef areas that are found within cracks and crevices form the interdial zone to depths of 330 feet. They reach a maximum length of 150 cm (59 inches). During the day they have only their heads protruding. The body shape and lack of fins, scales, or gill covers allows this species to move quickly in and out of rocky crevices, As such they are voracious nocturnal ambush predators with poor eye sight that utilize a keen sense of smell to seek out prey, consuming on small fish and invertebrates including crabs, octopus, and shrimp. They open and close their mouths frequently, an action that is required for respiration. Reproduction is viviparous with eggs and sperm broadcast into the water generating pelagic eggs and larvae that may drift in oceanic currents for up to a year before settling out on the bottom. The Panamic Green Moray is found in all Mexican waters of the Pacific with the exception of the extreme northern portion for the Sea of Cortez and north of Guerrero Negro along the northwest coast of Baja.
The Panamic Green Moray can be confused with the Fine-Spotted Moray, Gymnothorax dovii (omnipresent small white spots covering all parts of the body behind the head) and the Slender Moray, Enchelycore octaviana (beak-like head profile and a body with uniform coloration and no distinguishing marks).
The Panamic Green Morays are of limited interest to most fishermen and are normally a “catch and release.” Visually they are most intimidating but they are very timid and are not harmful and bites of humans are uncommon.