The most suitable tilapia species for the aquaculture industry grow fast and have a deep body shape, disease resistance, and the best adaptability to culture conditions.
Riverine tilapia species are more suited to the crowded conditions of aquaculture than lacustrine ones. Rivers in Southern Africa typically consist of smaller, harsher environments than the great lakes where lacustrine species have evolved.
Oreochromis mossambicus, O. andersonii, O. niloticus and Tilapia rendalli are all riverine species found in a wide range of habitats. There are, however, many other lesser-known species found outside our immediate geographical area.
Beware of inbred varieties
O. mossambicus is often inbred and genetically stunted in South Africa due to dams being stocked by poor, inbred stock. Government hatcheries have for many years practised little selection and improvement of brood-stock, and fingerlings from this source are best avoided.
Even the best quality O. mossambicus can take 10 to 12 months to reach a culture condition of 500g, and the species has the disadvantages of early maturation, precocious reproduction and poor body shape, with enlarged lips and head. There is an attractive orange variety available, however, that achieves higher consumer acceptance in some markets.
O. niloticus, on the other hand, has had the benefit of 30 years of selection and improvement on farms in Southeast Asia
and elsewhere. Strains that grow more than 60% faster with much-improved body shape, fillet yield and disease resistance are now available.
If you have a Nile tilapia culture permit, insist on one of these improved strains. GIFT, Thai or Taiwan red, Chitralada, FishGen, Til Aqua or similar strains are all good choices. Beware of ‘mongrel’ strains sourced locally in the Limpopo or Zambezi systems that may be hybrids.
O. andersonii is the species with the most potential for improvement. Being more cold-tolerant than O. niloticus as it originates from higher altitudes, it may be more suitable for cool-water culture. In its natural state, it is a deep-bodied, late-maturing species with a small head and high fillet yield. It is also known as one of the best-tasting species.
O. andersoni would be the species of choice for Botswana, Namibia and western Zambia on the Zambezi River, where it is indigenous.
T. rendalli is another deep-bodied species generally regarded as slower-growing. It has potential in areas where Nile tilapia is prohibited for conservation reasons as it will not hybridise with other local species. It grows to more than 2kg, and a programme of selective breeding could yield positive results. This species is largely herbivorous and is therefore attractive for the aquaponics industry.