There are 58 species of Clarias recognized in FishBase (as of January 2009), 33 in Africa and 25 in Asia. Aquaculture of clariids is important with 30 countries reporting a total production of over 300 000 t worth nearly US$400 million in 2006. Most production involves the African Clarias gariepinus (Burchell, 1822) and three Asian species, Clarias batrachus (Linnaeus, 1758), Clarias macrocephalus (Günther, 1864) and Clarias fuscus (Lacep'de, 1803). In much of Asia, hybrids of introduced C.
In many developing countries, availability of suitable tags for use in genetics and aquaculture research has been a problem as they are often expensive and have to be imported from other countries. A simple and inexpensive method used by scientists in Ghana that can be tried and improved by others is described in this article.
Second Workshop of the Genetic Improvement of Freshwater Prawn Macrobrachium rosenbergii, Central Institute of Freshwater Aquaculture, Bhubaneswar, India, 22-24 June 2009
The use of reproductive and genetic technologies can increase the efficiency of selective breeding programs for aquaculture species. Four technologies are considered, namely: marker-assisted selection, DNA fingerprinting, in-vitro fertilization, and cryopreservation. Marker-assisted selection can result in greater genetic gain, particularly for traits difficult or expensive to measure, than conventional selection methods, but its application is currently limited by lack of high density linkage maps and by the high cost of genotyping.
Many sources of information that discuss currents problems of food security point to the importance of farmed fish as an ideal food source that can be grown by poor farmers, (Asian Development Bank 2004). Furthermore, the development of improved strains of fish suitable for low-input aquaculture such as Tilapia, has demonstrated the feasibility of an approach that combines “cutting edge science” with accessible technology, as a means for improving the nutrition and livelihoods of both the urban poor and poor farmers in developing countries (Mair et al. 2002).
For the first time in India, selective breeding work has been initiated at the Central Institute of Freshwater Aquaculture, Bhubaneswar, India in collaboration with the Institute of Aquaculture Research (AKVAFORSK), Norway. Rohu has been chosen as the model species because it enjoys the highest consumer preference among Indian major carps (IMC) although its performance was observed to be slower than other IMC. As this was the first ever selection work on any Indian major carp, many procedures and techniques for successful implementation of the programs were standardized (i.e.
A fully pedigreed population of the GIFT (Genetically Improved Farmed Tilapia) strain of Nile tilapia (Oreochromis niloticus) was established in Malaysia during 2001 and 2002. The selection program was focused on the improvement of growth rate to harvest weight and the mate allocation strategy was aimed at avoiding inbreeding and ensuring that most sire families were represented as parents of the next generation.
The wide distribution and ongoing improvement of GIFT tilapia in Sri Lanka is raising the living standards of poor people and contributing to gender equality through employment for women in rural areas. So far, the GIFT fish have undergone four generations of selection for increased harvest weight in Sri Lanka. Now preferred in varied culture systems across the country, GIFT fish grow faster and have higher survival than local tilapia stocks.
Ability of fish to adapt to changing environments and stressors is a key trait for breeders, especially when they sell eggs or young fish all over the world. So far, this ability has not been introduced in any breeding program. Indeed, sensibility to environment is difficult to describe. Most often, either physiological traits, or behavioral traits are considered but each of them represent only a partial representation of the situation.
Aquaculture in developing countries is largely based on unimproved fish strains. There is ample evidence indicating the potential of genetic improvement programs and a range of selection methods may be used. Examples of the application of mass, cohort, within family, and combined between-within family are given. The methods are discussed in terms of their effectiveness and suitability.