• Organism

Tilapia

The mainstay of freshwater aquaculture, the Nile tilapia (Oreochromis niloticus) is a cichlid fish, originally from Africa.

Overview.

Species name

Nile tilapia (Oreochromis niloticus)

Sister-species (of interest) names

  • Lake Magadi tilapia     Alcolapia grahami
  • Mozambique tilapia    Oreochromis mossambicus
  • Rukwa tilapia             Oreochromis rukwaensis
  • Singida tilapia            Oreochromis esculentus
  • Shiranus tilapia          Oreochromis shiranus

The Nile Tilapia (Oreochromis niloticus) is a cichlid fish from Africa. Its native territory extends from the Nile River basins in Egypt along the Niger, Benue, Volta and Senegal rivers, and the Chad, Tanganyika, Albert, Edward and Kivu lakes.

It has since been introduced in over 50 countries and is widely used in aquaculture. The species has been very successful in areas of reintroduction due to its wide range of trophic and ecological adaptations, allowing it to occupy a variety of tropical/sub-tropical niches.

An omnivore that feeds on plankton and aquatic plants in shallow waters, typically during the day. This, along with its hardiness across different habitats, makes it a popular choice for aquaculture as it can be fed on pellet feeds, vegetation and agricultural waste; a more sustainable option than using predatory fish (e.g. salmon) which require a diet of fish feed.

Nile Talapia reproduce via spawning. The male prepares a nest in which the female lays her eggs for the male to fertilise them. The female then incubates them by putting them in her mouth (mouthbrooding), when the eggs hatch, the female continues to care for the young fish once they are free swimming, but still swim back into their mother's mouth for protection.

Quick Facts.

Status: N/A
Population:
Scientific name: Oreochromis niloticus
Average weight: 2.4kg
Average Size: Max. Length: 60 cm (24 inches)
Habitat: Freshwater/brackish - lakes/ponds, rivers, reservoirs, lagoons, estuaries.
Diet: Plankton and aquatic plants

Status: Vulnerable
Population:
Scientific name: Alcolapia grahami
Average weight: 9g
Average Size: Max. Length: 10 cm (4 inches)
Habitat: Hypersaline lake.
Diet: Algae, copepods and insect larvae

Status: Near threatened
Population:
Scientific name: Oreochromis mossambicus
Average weight: 620g
Average Size: Max. Length: 35 cm (14 inches)
Habitat: Freshwater - rivers and lagoons.
Diet: Phytoplankton, detrital material (rock particles), invertebrates, small fry and vegetation

Status: Vulnerable
Population:
Scientific name: Oreochromis rukwaensis
Average weight:
Average Size: Max. Length: 33 cm (13 inches)
Habitat: Freshwater - lakes and rivers.
Diet: Phytoplankton, higher plants, small animals (insects & their larvae, crustaceans and worms)

Status: Critically endangered
Population:
Scientific name: Oreochromis esculentus
Average weight: 2.5 kg
Average Size: Max. Length: 37 cm (15 inches)
Habitat: Freshwater - lakes, dams and rivers.
Diet: Phytoplankton, higher plants, small animals (insects & their larvae, crustaceans and worms)

Status: N/A
Population:
Scientific name: Oreochromis shiranus
Average weight:
Average Size: Max. Length: 39 cm (15 inches)
Habitat: Freshwater - lakes, rivers, streams and lagoons
Diet: Detritus and phytoplankton

Scientific significance.

Most of the world's capture fisheries are over-exploited and it seems inevitable that fish-farming will largely replace wild capture, just as livestock farming has replaced hunting as the main source of food from land animals.
 
Tilapia is one of the most widely farmed aquaculture species, with aquaculture production (in metric tonnes) growing by over 500% since 2000. However, the scientific value of Tilapia research extends far beyond aquaculture itself, where information on genetic traits enabling adaptation to various water conditions is beneficial.
 
Evolutionary biologists can benefit from a greater understanding of species relationships in a major group of cichlid fishes; a fascinating group of fish that have undergone rapid adaptive radiation in African rivers and lakes.

Conservation biologists can benefit from locating and identifying remaining natural populations of native tilapias to help in the design and implementation of conservation strategies focused around species of substantial economic benefit. Ecologically, tilapia species that are adapted to extreme conditions can also provide a valuable biological model to monitor the effects of hydrological changes in water ecosystems on living organisms.

Conservation.

While the Nile tilapia is not itself involved in conservation programmes, its usage in aquaculture has wide-ranging consequences for the biodiversity and conservation programmes of areas in which it has been introduced. It thrives in disturbed and harsh environments and can rapidly reproduce when it migrates to these areas due to it being a mouthbrooder. Consequently, native species will be quickly outcompeted in areas where it has been introduced or has escaped from enclosed areas - and therefore has become an invasive species in many ecosystems.

The Nile tilapia has long reproductive periods which can extend to most of the year (depending on its location) and, unlike most tilapia, has an omnivorous diet which grants access to other food sources. Furthermore, it can contribute to eutrophication of bodies of water which cause toxic algal blooms that suffocate fish populations. All of these factors threaten the indigenous populations of fish of the areas it occupies.

What Earlham Institute is doing.

Most tilapia production is based on a handful of strains, but there are more than 50 wild species throughout Africa that could harbour valuable genes for growth, disease-resistance, temperature and salt-tolerance. This knowledge opens up the potential of using stress-tolerant species in breeding programmes to develop fish farming strains resilient to adverse water conditions.
 
At EI, and in conjunction with several collaborators (Bangor University, South Eastern Kenya University and The University of Dodoma), we are using the power of genome sequencing to examine the genetic makeup of introduced and local tilapia species in African countries e.g. Tanzania and Kenya. In this way, we can use genetic markers for species identification and begin to understand whether parts of the genome are important in adaptation to different ecological gradients (salt-tolerance, pH sensitivity and thermal-tolerance).
 
Using this knowledge and the fact that tilapia will readily hybridise, natural genetic traits that are of benefit for aquaculture i.e. tolerance to adverse water conditions, could be easily bred into farmed strains without the need for GM technology.
 
All of this research is supported by funding from BBSRC and NERC.

Learn more.

For more general information about the Nile tilapia, you can look at its profile on the Centre for Agriculture and Bioscience International.  

For a brief overview of its role as an invasive species, then take a look at the Global Invasive Species Database.

If you are interested in reading more about how the Nile tilapia is an invasive species and the impact it has on ecosystems, then you can read the effects of introduced tilapias on native biodiversity.

Related reading.