Species of the week

Mozambican Tilapia, a fish with fertilization, eggs' incubation and juveniles' development in its mouth.

Common name: Mozambican Tilapia; Black Tilapia
Scientific nameOreochromis mossambicus

Class: Actinopterygii
Order: Perciformes
Family: Cichlidae
Genus: Oreochromis

Conservation status: Near Threatened

Diet: The individuals of these species are omnivorous and tend occasionally to be cannibals. Generally they feed themselves on algae filaments, aquatic macrophytes and small invertebrates when adult.

Size: The body size varies with environmental and reproductive pressure. Generally, the females can reach 25 centimeters and the males 35 centimeters, when they are adults, with average body weight of 1.1 kg.

Longevity: approximately 11 years

The Black Tilapia or Mozambican Tilapia (Oreochromis mossambicus) is an African cichlid, known as maternal mouth incubator, with a medium lateral compressed body and has a long dorsal fin with spines. Is greenish yellow colored when adult (apparently black) and slivery colored when juveniles. The males form aggregates in shallow waters during incubation period, where are established the territories through agonistics interactions between the males.

Due of its high olfactory sensibility to body fluids, the males use their urine as reproductive condition signal for females access and for territorial maintenance.


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Habitat

Oreochromis mossambicus generally is founded in freshwater for tropical and subtropical regions, as small lakes, coastal lakes and running water rivers. Due to their high salinity tolerance, individuals of this species can be found in estuarine environment and can proliferate in sea water. Ample diet is one of factor that allows this species occurrence in variety habitats.

Distribution

The Mozambican Tilapia is distributed over coastal areas in tropical and subtropical regions. Occurs principally in Mozambique, Malawi, South Africa, Swaziland, Zambia and Zimbabwe.

Reproduction

O. mossambicus has maternal polygamous behavior and reach its sexual maturity at two months with 6 – 28 centimeters of its body length. Its reproduction is over the year. During the reproductive period, after mating and ovulation, the female peek hundreds of eggs and sperm spread by dominant male and deposit into its mouth canal where will occur the fertilization and incubation process for 20 -22 days, using also, as juvenile refuge. The female leaves the aggregation during incubation period and the male mates with others females. The juveniles are kept in its mother´s mouth till they’ve developed survival capacity.

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Threats

The invasion of Mozambican tilapia´s natural habitat by Nile tilapia (Oreochromis niloticus) and high hybridization with the same species in aquaculture activities, represents the biggest threats for Mozambican Tilapia population

Curiosity

The Mozambican Tilapia is listed by Global Invasive Species Database (2006) as one of the major invasive species of the planet.


Sources

  • Almeida, O. G. (2014). Neuroendocrinologia do comportamento social no ciclídeo aficano Oreochromis mossambicus: mecanismos reguladores e modulação social da reprodução. Doutoramento em Biologia. Universidade do Algarve.
  • IUCN
  • Miranda. A., Almeida, O. G., Hubbard, P. C., Barata, E. N., & Canário, A.V. M. (2005). Olfactory discrimination of female reproductive status by male tilapia (Oreochromis mossambicus). The Journal of Experimental Biology 208, 2037 – 2043.
  • Oliveira, R. F., Silva, A. & Canário, V. M. (2009). Why do winners keep winning? Androgen mediation of winner but not loser effects in cichlid fish. Proceedings of the Royal Society. Biological Science. London

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