Tilapia; from the Nile to the World

Abstract This study addressed the potential of tilapia aquaculture as a major contributor to food production and poverty alleviation all over the world. To encompass this subject, tilapia history, origin, aquaculture potential, constraints, current and future production levels were reviewed. Tilapias are native to the River Nile and Africa in general then they were introduced and disseminated worldwide. Positive aquacultural characteristics of tilapia made tilapias the most cultured species worldwide now and in the near future. Tilapia world production is expected to reach 3 million tons this year 2010.

Thus, tilapias could make a significant contribution to the livelihoods support especially in the tropical and subtropical countries. Key words: Tilapia, Oreochromis, Sarotherodon, introduction, production, River Nile. INTRODUCTION Tilapia is the second world wide cultured species after carps. They are also known as “Aquaculture Chicken” as they are present in all continents except Antarctic. Tilapia culture goes back to the ancient Egyptians who cultured Nile tilapia in ponds around 5000 years ago as indicated by paints on the walls of Pharaohs’ tombs.

Moreover, tilapia has a Hilogryphs and was known as in. t. Aristotle named it as “Nile Tilapia” or fish of the Nile; 300 years BC. Thus, Tilapia is native to the Nile River (Fig. 1) and to Africa in general (1 and 2). Tilapias were then introduced to many countries in the 1950's and 1960's as a "wonder fish". Although tilapia had certainly, a major impact on aquaculture developments in Asia and the Pacific since the 1970s, there are some claims that tilapias are invasive and affected the native species in the natural water ecosystems.

However, there is scant explicit evidence to indicate that tilapias have been overly destructive environmentally (6). Such claims frightened and prevented some countries such as Australia to introduce tilapia culture to their lands. Therefore, the objective of this study is to review tilapia production, the constraints hindering global tilapia culture and to discuss the suggested solutions as well as future perspectives. Fig. 1 Map of the River Nile Taxonomical classification

Recently, there are 3 main genera of tilapia (under family Cichlidae) according to the reproductive behavior; Oreochromis (Females only are mouth brooders), Sarotherodon (both males and females share in the process of mouth incubation of eggs, larvae and frys) and Tilapia (substrate breeders) (Figs. 2 & 3). Before 1970s, all tilapia species were categorized under 1 genus; tilapia. Commonly, tilapia nilotica is still used by some scientists who don’t accept the modern classification (1). Fig. 2 The most common Tilapia species and hybrids Fig. 3 Reproductive behavior of tilapia; Oreochromis niloticus

Introduction of tilapia to Asia and to the world Although aquaculture is considered an old tradition, modern aquaculture is essentially a post-1950 phenomenon. O. niloticus became the preferred tilapia species for aquaculture in the region (3). Although it is difficult to assess whether this species has made a significant contribution to the animal protein needs of rural Asian communities, it certainly had a major impact on aquaculture developments in Asia and the Pacific since the 1970s. Twelve tilapia species (six Oreochromis spp. ; two Sarotherodon spp. ; and four Tilapia spp. ) and one hybrid have been introduced into 30 Asian countries.

Of the species introduced to Asia, O. mossambicus and O. niloticus are by far the most important from both production and scientific points of view. These species are now widely distributed in most of Asia and occur in natural and quasi-natural waters making them a part of the fish fauna of most of tropical and even sub-tropical Asian aquatic environments (4). The "red tilapia", a hybrid between strains of O. mossambicus x O. niloticus is currently considered as important to aquaculture in Asia (5). In general, Tilapias have been introduced into over 90 countries worldwide, with a global distribution second only to common carp.

Although tilapia has been associated with adverse environmental impacts, detailed analysis of the literature suggested that other factors, such as over fishing, environmental degradation from land-based activities, and changes in hydrological regime have probably been more responsible for adverse impacts. It is clear that numerous factors working together can impact biodiversity. It is also clear that tilapias, as a group of alien species, have made a significant contribution to food production, poverty alleviation and livelihoods support in Asia and the Pacific.

In spite of the wide-scale introduction into Asian waters, there is scant explicit evidence to indicate that tilapias have been overly destructive environmentally (6). Thus, Asian countries are major producers and consumers (7) Tilapia Production The current aquaculture production (2002) of tilapias is about 1. 5 million tones, the great bulk of which takes place in Asia accounting for nearly 80 percent of the total world production. It is important to note, however, that tilapia culture in Africa and South America is also increasing. Prior to the mid-1990s, the yield of tilapia from capture fisheries was greater than that from aquaculture.

Currently, the later accounts for approximately 2. 5 times the production from capture fisheries. Tilapia aquaculture production increased from 28 000 tons to 1. 504 million tons globally from 1970 to 2002; in Asia and the Pacific, production increased from 23 000 tons to 1. 192 million tons equivalent to an annual growth rate of 13. 2 percent and 13. 1 percent, respectively. In contrast, capture fisheries for tilapias have grown at the rate of 3. 5 percent per annum. China alone produces nearly half of the world tilapia production followed by Egypt, Indonesia, Philippines, Thailand and Taiwan (Fig. ). Tilapias can be reared in ponds, tanks, cages and rice fields. Fig. 4 The highest ranked countries in Tilapia production Constraints of Tilapia culture •Over-population due to early sexual maturity of tilapia. •Cold sensitivity. •Vulnerability for toxins of blue green algae in case of tilapia monoculture. •Claims of invasiveness of tilapia. Suggested solutions and useful practices •Production of monosex tilapia via Genetic hybridization. •Avoid hormonal monosex production. •Sterilization. •Polyculture with predators like catfish. •Crossing with cold resistant strains such as O. ureus. •More research is still needed to mitigate the sensitivity to blue green algae’s toxin. CONCLUSIONS AND FUTURE PERSPECTIVES Positive aquacultural characteristics of tilapia as their tolerance to poor water quality, easy spawning, biological controllers for aquatic weeds and mosquitoes as well as the fact that they eat a wide range of natural food organisms make tilapias the most cultured species worldwide now and in the near future. Tilapia world production is expected to reach 3 million tons in this year 2010 (Fig. 5) (double of tilapia production in 2002).

Thus, tilapias could make a significant contribution to food production, poverty alleviation and livelihoods support all over the world especially in the tropical and subtropical countries. Fig. 5 Future global tilapia production from aquaculture REFERENCES 1- SRAC; Southern Regional Aquaculture Center (1999): “Tilapia Life History and Biology”. SRAC Publication No. 283. 2- www. miami-aquaculture. com 3- Smith, I. R. and Pullin, R. S. V. (1984): “Tilapia production booms in the Philippines”. ICLARM Newsletter 7: 7 - 9. 4- Pethiyagoda, R. (1994): “Treats to indigenous freshwater fishes of Sri Lanka and remarks on their conservation”.

Hydrobiologia 285: 189 - 201. 5- Welcomme, R. L. & Vidthayanon, C. (1999): “Report on the impacts of introductions and stocking in the Mekong Basin and policies for control. Management of Reservoir Fisheries in the Mekong Basin”, Phase I. Phnom Penh, Cambodia, Mekong River Commission, 62 pp. 6- De Silva, S. S; Subasinghe, R. P. ; Bartley, D. M. ; Lowther, A. (2004): “Tilapias as alien aquatics in Asia and the Pacific: a review”. FAO Fisheries Technical Paper. No. 453. Rome, FAO. 2004. 65p. 7- Kevin Fitzsimmons (2008): “Global Update 2008: Tilapia Production, Innovations, and Markets”. Orlando, FL, Aquaculture America, Feb 2008.

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