Mozambique Tilapia, Oreochromis mossambicus
Mozambique Tilapia, Oerochromis mossambicus. Fish caught with a cast net out of an irrigation pond of the greater Los Cabos area, Baja California Sur, February 2008. Length: 26 cm (10 inches). Identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, California. Smaller versions that are less than 17 cm (6.5 inches) in length are also present in the San José River basin, Baja California Sur.
Mozambique Tilapia, Oerochromis mossambicus. Fish caught from an irrigation canal in the greater Sebastian, Florida area, March 2021. Length: 28 cm (11 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
The Mozambique Tilapia, Oreochromis mossambicus, is a member of the Cichlid and Talapia or Cichlidae Family, and is known in Mexico as tilapia del Mozambique. They are native to Southern Africa and via human introductions they are now found throughout the global tropical and subtropical locations. Globally, there are thirty-two species in the genus Oreochromis, of which four are found in the majority of freshwater systems within Mexico. They were introduced and cultivated in Mexico in the 1950s with fish being imported from Africa.
The Mozambique Tilapia has an overall “bluegill profile” with a deep compressed body. Coloration can vary significantly and they can be blue, black, dull greenish or yellowish with the lower portion of the head being white. The margins on the caudal and dorsal fins are red with weak banding. They are dimorphic and when spawning the caudal and pectoral fins becoming reddish with the males’ tail being a brighter orange than those of the females. Females and non-breeding males are silvery with 2 to 5 mid-lateral blotches and 3 or 4 dorsal blotches. The males have have an upper jaw length and the mouth that is larger than those of the females and also a blue upper lip. The head is mid-sized with modest sized eyes and they have a knob like protuberance behind the upper jaw. The anal fin has 3 spines and 9 or 10 rays; the caudal fin is rounded; and, the dorsal fin has 15 to 18 spines and 10 to 13 rays and is continuous with a long base. They have 16 to 22 gill rakers on the first arch. The lateral line is interrupted and the body is covered with cycloid scales.
The Mozambique Talapia is found in rivers and lagoons predominantly in fresh water but they can also tolerate fairly high levels of salt and are also found in brackish waters normally with dense aquatic vegetation. They are residents of all Mexican freshwater environments that do not drop below 11oC (52oF). They reach 40 cm (16 inches) in length and 1.1 kg (2.5 lbs) in weight, with males being larger than females. As of January 1, 2024, the International Game Fish Association world record stood at 3.11 kg (6 lbs 13 oz) with the fish caught in fresh water later in South Africa in April 2003. They are opportunistic omnivores consuming diatoms, invertebrates, small fry and vegetation ranging from microalgae to rooted plants to decaying plant material. They are active diurnally. Reproduction occurs year round when water temperatures are in excess of 20oC (68oF) with each female raising new broods every 3 or 4 weeks. There is intense competition among the males for nesting sites. Once selected the males excavate a three-foot diameter saucer shaped nest in sand or small gravel in which the females lays her eggs. After fertilization by the male the female collects the eggs and stores them in her mouth until the fry hatch (mouthbrooding) in 1 to 3 weeks and the fry remain for another 2 weeks. They exhibit a high level of parental care with the females caring for the young and the males providing protection. These families are thus highly mobile. These proficient reproductive strategies are supportive of their invasive tendencies. They have lifespans of up to eleven years.
Mozambique Tilapia is similar to, and can be mistaken for the Blue Tilapia, Oreochromis aureus (18– 26 gill rakers on first arch) and the Nile Tilapia, Oreochromis niloticus (27–33 gill rakers on first arch).
The Mozambique Tilapia is present in all freshwater systems of Mexico.
From a conservation perspective the Mozambique Tilapia is currently considered to be NEAR THREATENED. When introduced to bodies of water that contain the Nile Tilapia, Oreochromis niloticus, the two readily mate which leads to hybridization and to the long term extinction of the Mozambique Tilapia in those systems is assured. As approximately 50% of the current native locations for the Mozambique Tilapia have not yet invaded by Nile Tilapia significant efforts are ongoing to protect these systems from deliberate and accidental introductions of Nile Tilapia. They provide strong competition with native fishes for nesting places and food including the direct consumption of small fishes. As such the Mozambique Tilapia has the dubious distinction of being considered to be one of the 100 worst invasive species in the world. Mozambique Tilapia can be used as aquarium fish, however they become excessively large very quickly. They are also a dirty fish that requires frequent water changes and old species become increasingly aggressive. They are also used to bioassay organisms to generate metal toxicity data for risk assessments of water bodies containing local freshwater species. The introductions of the Mozambique Tilapia have been wide-spread having been introduced into water systems by anglers, fish farmers and government agencies, for aquatic plant control, insect control, sport fishing, bait fish, and as a food fish and through aquarium releases, escapes from fish farms, hatcheries, and zoos. They are a prime farmed fish because they are hardy individuals that are highly adaptable to new environments, differing water conditions, changes in food supplies, and have a high tolerance for high levels of ammonia, low levels of oxygen, general pollution and have an ability to survive drought by burying in moist sand. They can grow and reproduce in waters with a relative high salt content. It is a popular food fish with white, mild flesh and they are marketed live, fresh and frozen. The Mozambique Tilapia, is more commonly used for hybridization with other tilapia species. The hybrids grow faster, have a better body shape, and in some species the populations will be predominantly male (which will grow faster to a uniform size). Under crowded condition cannibalization will occur and also the fish will become stunted. This species is produced at a level of 40,000 tons per year and constitutes about 4% of the total global tilapia aquaculture production. Mexico is currently only a small player in this global market.