Mountain Mullet, Dajaus monticola
Mountain Mullet, Dajaus monticola. Fish caught from the freshwater systems of Stuart, Florida, April 2021. Length: 7.8 cm (3.1 inches). Catch, photograph and identification courtesy of Ben Cantrell, Sebastian, Florida.
Mountain Mullet, Dajaus monticola. Fish caught from a freshwater stream in Puerto Chomes, Costa Rica, March 2021. Length: 26 cm (10 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
Mountain Mullet, Dajaus monticola. Fish caught from a freshwater stream in Puerto Chomes, Costa Rica, March 2022. Length: 26 cm (10 inches). Catch, photograph and identification courtesy of Thomas Enderlin, flyfishingcostarica.com.
The Mountain Mullet, Dajaus monticola, is a member of the Mullet or Mugilidae Family, that is known in Mexico as lisa de río, trucha tepemechín, and trucha de tierra caliente. The Mountain Mullet has recently been reclassified from Agonostomus monticola to Dajaus monticola. Globally, this is the only species in the genus Dajaus, and it is found in Mexican waters of both the Atlantic and the Pacific Oceans.
The Mountain Mullet has an elongated and slightly compressed robust body. They are a grayish-brown or olive color dorsally that transitions to white ventrally with the scales having dark margins that provide a crisscross pattern on the upper body. Their fins are pale yellow with the first third of the pectoral fins being dark. Their iris is golden, reddish above, and dusky before and behind the pupil. The juveniles have a dark blotch on the pectoral fins and a dark spot at the base of the caudal fin. The anal fins have 2 spines and 9 rays; their caudal fin is weakly forked; their first dorsal fin has 5 slender spines; their second dorsal fin has 8 rays; their pectoral fins are high on the body; and, their pelvic fins are found behind the pectoral fins. They have 17 to 20 gill rakers on the lower limb of the first arch. Their head is convex between the eyes, has a relatively small mouth and opens in the front that has thick top and bottom lips with a rounded lower jaw that is equipped with a continuous of imbedded bands of teeth. They are covered with large rough scales. They do not have a lateral line.
The Mountain Mullet is found in marine, brackish and freshwater systems and is diadromous living in both freshwater and saltwater during different parts of their life stages. They spend most of their adult live In fresh water being found far upstream at elevations up to 1,500 m (4,900 feet) in high gradient streams with fast moving water with strong currents and rocky bottoms with water temperatures between 20oC (68oF) and 31oC (88oF) . They are a pelagic species that can be found as solitary individuals or in large schools within estuaries. They rely on large schools for protection against predation. They are found near the surface at depths less than 5 m (16 feet). They reach a maximum of 36 cm (14 inches) in length. The females are larger than and slightly outnumber the males. They are omnivores that feed on algae, plant detritus, mollusks, small freshwater shrimp, snails, and tiny aquatic insects. They are preyed upon by birds, fish, and various other marine mammals. Reproduction occurs during the rainy season and is oviparous with external fertilization by the males. Some populations are believed to be amphidromous, spawning in freshwater, with the eggs drifting to sea, where they hatch and larvae grows at sea before returning to freshwater as juveniles. Others are catadromous spawning in marine environments. Each female releases 300,000 to 350,000 eggs, that are fertilized externally by the males, that are non-adhesive and pelagic. The eggs hatch as sea and remain there for an extended period of time before the juveniles move to fresh water. The Mountain Mullet 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 Mountain Mullet is found along the coasts of all Mexican waters of both the Atlantic and the Pacific Oceans being more common in southern regions and virtually non-existent in others.
The Mountain Mullet can easily be confused with the the Bobo Mullet, Joturus pichardi (11 anal fin rays; 10 dorsal fin rays; mouth opens under the snout), the Striped Mullet, Mugil cephalus (adipose eyelid, thin lower lip, more than 25 gill rakers, lighter color) and the White Mullet, Mugil curema (adipose eyelid, thin lower lip, more than 25 gill rakers, lighter colored).
From a conservation perspective the Mountain Mullet is currently considered to be of Least Concern with stable, widely distributed populations. They are an important commercial species that are caught with cast nets, lift nets, stake nets, trammel nets, beach seines, hook and line and fish corrals. They are marketed year-round fresh, frozen and salted for human consumption. They are perused by recreational anglers on a limited basis. Juveniles are utilized as a live bait fish. The are important to the Mexican economy as Mexico is one of the top ten global countries for mullet with annual production at the level of 12,000 tons per year.