Nile tilapia, cichlid, mango fish, mozambique tilapia

Type Description

"Number of dorsal spines 15-18; number of dorsal soft rays: 11-13; number of anal spines 3; number of anal soft rays: 9-11. The number of vertebrae varies between 30 and 32. It is a large tilapia with a relatively small head and deep body (Genner et al., 2018).
Their most distinctive feature is the presence of regular vertical stripes along the caudal fin depth (Eccles, 1992; Teugels and Thys van den Audenaerde, 2003). In all life stages, the caudal fin is marked by numerous thin vertical stripes; in small fish, these are relatively broad; they form an arc and begin at the base of the caudal surface (Genner et al., 2018)."

Habitat

"They are found in a wide variety of freshwater habitats such as rivers, lakes, sewage channels, and irrigation canals (Bailey, 1994). Surviving in saltwater is difficult for them, but they can endure in brackish water (Lamboj, 2004).

This species is a freshwater cichlid native to the Nile River basin; Middle East; Niger, Benue, Volta, and Senegal rivers; and Chad, Tanganyika, Albert, Edward, and Kivu lakes (Trewavas, 1983; Daget et al., 1991) and is distributed across all continents except Antarctica (in more than 50 countries) - mostly spread for agricultural purposes (Pullin et al., 1997).

There are some gaps in the knowledge of the species' distribution. These knowledge gaps make it difficult to precisely identify the areas where Nile tilapia has spread and predict potential areas of spread.

The entry pathways of the species into new localities are listed as aquaculture (Nico and Schofield, 2011), reproduction and proliferation (Canonico et al., 2005), escape (Canonico et al., 2005; Nico and Schofield, 2011), fisheries (Canonico et al., 2005), and deliberate release (Canonico et al., 2005).

At the forefront of the local distribution pathways of the species are escape and fishing activities."

Reproductive Information

Females deposit their eggs in the nest prepared by the male, where the male fertilizes the eggs, and then the female picks up the fertilized eggs and incubates them in her mouth. Even after hatching, the fry remain in the mother's mouth. After swimming freely for a while, the fry will return to the female's mouth for protection. Females can produce several hundred to several thousand fry per spawning.

Lifecycle

"They reach sexual maturity in 3-6 months depending on temperature. Reproduction occurs only when temperatures are above 20°C. Females incubate their eggs in their mouths for about a week. Egg size is about 1.5 mm, and larval length at hatching is around 4 mm.

They spawn in shallow nests in lakes at depths of 0.6 to 2 m and in hard sand in coastal waters (Trewavas, 1983; Worthington, 1932). Males establish and defend nesting sites, a process that lasts several hours. A male may fertilize the eggs of multiple females (Worthington, 1932). Eggs are laid in shallow nests in groups and fertilized by the male. Each group of eggs is taken into the female's mouth."

Nutrition Information

They primarily feed on phytoplankton or benthic algae. Additionally, they consume insect larvae and detritus; juveniles tend to be more omnivorous than adults (Lamboj, 2004).

General Impact Information

"Oreochromis niloticus has had a significant impact on increasing food production by creating livelihoods through alternative aquaculture and fisheries (Wise et al., 2007).

Environmental Impact: The spread of this species has been associated with significant environmental changes, particularly related to the construction of reservoirs and large-scale irrigation projects. Many populations have been so successful that they have become a permanent part of fish communities. Introductions of these species into water bodies are likely to develop large populations and create male breeding territories. Aggressive defense of male nesting areas may affect native nest builders.

Impact on Biodiversity: This species is distributed across tropical regions. In many cases, this distribution has occurred before any scientific assessment of natural water ecosystems. In most cases, the environmental effects are at the assumption stage.

This species is listed on the blacklist of the IUCN Global Invasive Species Database."

General Management Information

"Prevention: A precautionary approach is recommended when deciding which species to use and where for aquaculture, particularly in areas considered suitable for the cultivation of this species. The spread of the species should be restricted to its former basins and prohibited in areas that have not yet been invaded. Additionally, where possible, the species should be eradicated from non-invaded river systems.

Alternatively, the use of native species can be promoted and developed through stock enhancement and improved farming practices. However, these alternative species should not be introduced into new river systems outside of their native rivers, as they may pose invasion-related problems.

Domestication and Breeding: There are some steps aquaculture activities can take to minimize any additional harm to the species. Industrial activities continue to impact the species.

The establishment of strains of Nile tilapia is a significant step, as these strains are found only in domestic populations and have little chance of survival in the wild. They are highly vulnerable to predation by birds, fish, and humans, as they are highly visible in water. Strains bred for high flesh content and a more rounded body shape are also unlikely to survive outside of a farm. Finally, all-male populations developed from hybrids, sex-reversed individuals, or genetically male parents are less likely to establish a breeding population outside of farms.

It should be noted that all of these techniques contribute to reducing the tilapia's ability to impact local communities."

General Pathway Information

Entry pathways into our country: Aquaculture, fisheries, escape

Notes

"Oreochromis niloticus is a species commonly used in laboratories and research. Additionally, they are assessed in botanical gardens and zoos. They are also subjected to recreational fishing and are consumed as human food (whole, filleted, fresh, frozen, canned, processed).

Tilapias, constituting 4% of global aquaculture production, are the third most cultured fish species in the world after carps and salmonids (FAO, 2010). Aquaculture is seen as a means of protein security, poverty reduction, and economic development in many developing countries (NEPAD, 2005).

Nile tilapia is highly suitable for aquaculture due to its diverse trophic and ecological adaptations, allowing it to occupy various tropical/subtropical freshwater niches (Trewavas, 1983).

Alongside Mozambique tilapia (Oreochromis mossambicus), Nile tilapia is the most important tilapia species in aquaculture. They are among the top ten most widely distributed fish species globally and account for 99.5% of global tilapia production (FAO, 2010). Since the mid-1980s, there has been a shift in producer preference from Mozambique tilapia to Nile tilapia culture because the latter has a higher growth rate."

References