Rainbow Scorpionfish, Scorpaenodes xyris
The Rainbow Scorpionfish, Scorpaenodes xyris, whose common Spanish name is escorpión arcoiris, is a species in the Scorpionfish or Scorpaenidae Family, known collectively as escorpiónes, rocotes or lapóns in Mexico. Globally, there are twenty-six species in the genus Scorpaenodes, three of which are found in Mexican waters, two in the Atlantic and one in the Pacific.
The Rainbow Scorpionfish have relatively slender compressed bodies with a depth that is 29 to 31% of standard length. They are various shades of red and brown with a significant amount of mottling often with three to five irregular dark bars on their sides. Their fins have white broken stripes except for the first dorsal fin which is a more uniform color. They have a white bar below their eyes that extends across their upper jaw and a prominent black spot on the lower portion of their gill cover. Their head is large but streamlined and has a terminal mid-sized mouth with teeth only on the roof. Their eyes are relatively large. They lack the “pit” after the eyes found in most other Scorpionfish. They have a longitudinal ridge under their eyes with two or three spines. Their anal fin has 3 spines, the second being exceedingly long and stout, and 5 rays; their caudal fin is rounded with a ragged margin; their dorsal fin has 13 spines and 10 rays; and their longest pectoral fin is in the center. Their lateral line is complete. They have no skin flaps and their body is covered with rough scales.
The Rainbow Scorpionfish are a fairly common but inconspicuous species found in cracks, crevices and under ledge overhangs within rocky reefs, steep slopes, and on walls from the intertidal zone to depths of 165 feet. They reach a maximum length of 15.0 cm (5.9 inches). Juveniles are found in close proximity to the Long Spined Urchin, Diadema mexicanum, presumably for protection against predation. They are common but seldom seen by humans.
In Mexican waters the Rainbow Scorpionfish are found in all waters of the Pacific with the exception that they are absent from of the extreme northern portions of the Sea of Cortez.
The Rainbow Scorpionfish is most likely confused with the California Scorpionfish, Scorpaena guttata (dorsal fin with 12 spines and nine rays; large bulbous head; pit behind eyes) and juvenile Stone Scorpionfish, Scorpaena mystes (dorsal fin with 12 spines and nine rays; large bulbous head; pit behind eyes).
The Rainbow Scorpionfish are too small to be of interest to most and difficult to handle, thus are a “catch and release”. From a conservation perspective they are considered common and classified as of Least Concern, however, populations are not currently monitored. Caution: As with all Scorpionfish, the Rainbow Scorpionfish should be treated as hazardous and released as soon as possible, being careful not to allow their poisonous spines to penetrate the skin.
Rainbow Scorpionfish, Scorpaenodes xyris. Fish caught from coastal waters off Santa Catalina Island, California, September 2016. Length: 13.0 cm (5.1 inches). Catch courtesy of Marty Dufek, Long Beach, California. Photo and identification courtesy of Chris Wheaton, Fullerton, CA.