Nile tilapia belongs to the class of the ray-finned fishes, to the order of Perch-like fishes and to the family of Cichlids and is therefore a relative of many ornamental fishes. Its origin are lakes, inland and coastal rivers of middle Africa and Near East. Although it is regarded as potamodrom (wandering in fresh water only) it lives as well in brackish water and can even adapt to salt water.
The members of this species dwell at the surface or in depth to 6 or even 20 meters and prefer water temperatures between 16 and 29 °C. In the active part of their day they swim in shoals whereas they retire to rest preferably during the night.
Tilapia prefer complex habitats with muddy or sandy or gravel bottoms where they find shelter from predators (including elder conspecifics) but can be found also in open waters. They feed near the bottom on phytoplankton (algae etc.) and invertebrates mainly. Adults measure between 20 and 60 cm and weigh between 130 g and over 4 kg.
Nile tilapia can live for up to nine years of age but reach maturity within only 3 to 7 months. Courtship lasts several hours, the male gently bits or nudges the female, swims in front of her and leads her to the spawning site, a nest in shallow water that he built in firm sand. After fertilization the female carries up to 240 eggs in her mouth during 7 to 18 days until the larvae hatch.
The species is very prolific and spawns several times a year. Because it has been easy to reproduce and to farm since the ancient Egyptians it has been introduced in many countries, including Southern Africa, Southeast Asia, USA or Mexico.
As males grow faster and bigger, male-only ponds have become an industry standard since the 1970s. Hatcheries deliver male-only juveniles produced by feeding sex hormones to the fry or by hybridization when crossbreading various tilapia species or strains. Apparently the impacts of mono-sex shoals on the animals have not yet been studied.
One advantage of Nile tilapia farming would be that the biology of the species does not require fish components in its feed. But if you have a look at the criteria of the leading labels for sustainable aquaculture you will learn that fish meal and fish oil plays a role as growth promoter also in the tilapia farming industry. Fish components are not only expensive but ecologically questionable as they mainly originate from specialized forage fishery that requires one fourth to one third of the global catch. This is in contradiction to sustainability and impairs the marine food chain and consequently the living of marine animals, thus animal welfare. Not to mention the welfare of about 450-1000 milliard* fishes caught for feed annually. Moreover, feeding fish meal and fish oil to tilapia gives a bad example for the widespread small and extensive tilapia ponds run for local supply in Africa and Asia.
* Milliard in FishEthoBase = a thousand millions
Today, Nile tilapia with its various strains is the second most farmed fish species worldwide, due also to its easy to fillet body and its consumer friendly taste and texture.
It is all the more amazing that a species farmed for such a long time, in so many regions of the world and in such quantities does not seem to have adequate priority for ethological research.
Hence recommendations on fish welfare for farmers are still limited, but the few that are certain rather challenge common practice. For example Nile tilapia need individual access to daylight as well as to darkness and to opportunities for withdrawal. Instead they are often kept in covered tanks without any structure.
Labels are not helpful for clients who care for the welfare of farmed fish. The guidelines of organic labels are the ones most inclined to grant animal welfare, yet they define no tangible instruction. All other labels address animal health at best, but do not acknowledge all-encompassing aspects of animal welfare. That is to say that even fishes farmed under labels like organic, ASC, or Friend of the Sea, often live under the conditions of intensive animal husbandry.
If we want to change the disregard for animal welfare, we need more of two things: ethological research and pressure from concerned consumers who want to eat respectfully-farmed fish.