1.0 INTRODUCTION
1.1 Background of the Study
With global population expansion, the demand for high quality animal protein is rising dramatically (Yisa et al., 2006). Increased aquaculture production is clearly needed to meet this demand, because capture fisheries are showing serious decline due to over fishing, aquatic habitat destruction and pollution (FAO, 2004). World capture fisheries have been in a stable state throughout much of the past decades, and it has been estimated that maximum capture fisheries potential from global waters has been reached .In 2007, as many as 50 percent of stocks were labelled as fully exploited (FAO, 2008).
Fish is an important and the cheapest source of animal protein and account for about 37% of Nigeria total protein requirement (FAO, 2002). Fish provides approximately 16% of the animal protein consumed by the world population (FAO, 1997). It is particularly an important protein source where livestock is relatively scarce. Billions of people mostly in developing countries depend on fish as a primary source of animal protein (FAO, 2000). FAO estimated that by the year 2010, demand of fish will increase by 13.5%-18.5% or to about 105-110% millions metric tons (FAO, 2000). Further increase in capture fisheries are not anticipated under the current global condition (Ounham et al., 2001). Faturoti (1999) noted that recent trends all over the world pointed to a decline from capture fisheries which are all indicators that fish stock have approached or even exceeded point of maximum sustainable yield. The Food and Agriculture Organization recommended that an individual takes 3 series per capture of animal protein per day for sustainable growth and development (FAO). However, the animal protein consumption in Nigeria is less than 8g per person per day which is a far cry from the FAO recommendation. The rapid growth of Nigeria population has lead to insufficiency in supply of animal protein food. Fish is a major source of animal protein and an essential food item in the diet of many people in Nigeria. Fish is also a good source of Thiamine, Riboflavin, Vitamin A and D, Phosphorus, Calcium, and Iron. It is also very high in polyunsaturated fatty acids which are important in lowering blood cholesterol level, it is therefore suitable for complementing high carbohydrate diets typical of low income group in Nigeria (Areola, 2008). Apart from being food, fish is also an important source of income to many people in developing countries including Nigeria. FAO (1996) confirms that as much as 5% of the African population have 35million people depending wholly or partly on fisheries sector for their livelihood.
However, the importance of fish in the diet of Nigerians, further significantly increased after the Sahara drought of 1971 to 1979. This drought which greatly decimated the cattle population made the price of livestock virtually unaffordable in major parts of Nigeria. This trend thus triggered an increase in the demand for fish as an alternative source of animal protein (Anadu et al., 1993).
Fish farming is increasing in Nigeria today, if this development is sustained, then aquaculture will create a great impact on the economy and provide proteinous food for its population (Alatise et al., 2006). Aquaculture therefore remains the only viable alternative for increasing fish production in order to meet the protein demand of people (Omotoyin, 2007). One of the objectives of aquaculture is the increase in the production and growth rate of fish that will meet the demand of the increasing population.
Catfish of the family Claridae comprise the most commonly cultivated fishes in Nigeria, the growth of aquaculture in Nigeria is now largely being boosted by a steady rise in catfish culture, with inadequate availability of seed stock and feed being the major challenges.The favoured catfish species in Nigeria aquaculture includes Clarias gariepinus, Heterobranchus bidorsalis and Heteroclarias. Heterobranchus species is the more commonly cultured fish in the South eastern parts of Nigeria. Africa catfish is popular in the market and has great potentials to boost the rapidly growing Nigeria aquaculture. Clarias gariepinus is generally considered to be one of the most important tropical fresh water fish species for aquaculture whose aquaculture potential have been documented (Dada and Wanah, 2003). Bruton (1979) pointed out that C.gariepinus has also high fecundity rate, grows faster, tolerates high density and environmental extremes. It also accepts wide range of natural and artificial food and adapts to a variety of feeding modes in expanded niches.
Clarias gariepinus has an almost pan-African distribution ranging from the mili to West Africa and from Algeria to Southern Africa. They also occur in Asia Minor (Isreal, Syria and South of Turkey). Clarias gariepinus at various geographical locations bears different values. It is called Clarias lazera in Northern and central Africa, Clarias gariepinus in South Africa (Viveen, et al., 1985). In C.gariepinus , exchange of respiratory gases (oxygen and carbondioxide ) takes place through the gills. Like other mudfish, it has accessory breathing carborescent organs which enable the fish not only live in stagnant pools but to travel over damp ground. Clarias gariepinus differs from other catfish in having an auxiliary breathing organs in this special pochet attached to the second and fourth gill arches and are responsible for the ability of Clarias gariepinus to live out of water much longer than other catfish (Haylor, 1993).
Feed, being part of the general input of production in extensive and semi-intensive sustainable aquaculture system, has been reported to account for 40-60% of the total recurrent cost of production (Falaye, 1992). Fish nutritionist aim at producing a balanced commercial diet that promotes optimal fish growth and health. The quality of commercial feed should be determined for individual feeds to carefully monitor the feed consumption and growth rate of the fish. Good quality feed and optimum feeding frequency may provide maximum utilization of diets and thus, fast growth of the fry and feed utilization in two Asian catfishes (Hung et al ., 2001; Dwyer et al.,2002). However, poor quality fish feed leads to leaching of nutrients, reduction in feed conversion ratio and increase in input list, and also, accumulation of wastes that adversely affect the water quality (Yakubu et al., 2013; Neoske and Spieler, 1984) . Therefore, it is important to standardize the quality of commercial feed for the target species in aquaculture for optimum production. The culture of fish is receiving a lot of attention in Nigeria with the result that new cultivation techniques are being introduced and adopted. Over the last decade, spectacular growth has taken place in aquaculture in Nigeria. Fish farming activity in Nigeria started about 50 years ago (Olagunju et al., 2007) and as at now aquaculture in the country is in the developing stage, because it has not been able to meet the demand of the ever increasing population (Ojutiku, 2008). Fish feeds are used in aquaculture to increase production and maximize profit. Feeds in intensive fish culture consume about 60% of the capital cost (Eyo, 2001).
For aquaculture to be highly successful in Nigeria there is need for good quality and affordable feed, which can also encourage small scale farmers in the field of aquaculture for sustainable production and also meet the demand for fish. Presently, in Nigeria, there are different fish feeds with different compositions ranging from Coppens, Vital feeds, Skretting feeds and others but there is competition among them. The amount of feed consumed, age, body size and temperature are the most important factors that limit maximum growth of fish (Machiels and Henken, 1985).
1.2. STATEMENT OF PROBLEM
One of the major problems confronting the development of aquaculture industry in Nigeria is availability of affordable and high-quality fish feed. Fish growth and survival rate depend on the kind of feed, feeding frequency, feed intake and the fish’s ability to absorb the nutrients. Once fish are removed from natural environment to artificial , enough feed must be supplied in order for them to grow. This could be in form of complete rations, where the artificial diet furnishes all the nutrients required by the fish. Both intensive and semi-intensive fish culture systems involve input of complete commercial feed which account for up to 60% of production costs (NRC 1993; Fagbenro et al., 2003) and can sometimes negate the economic viability of a farm if suitable feed are not used. This problem has become a major source of fear and phobia to many prospective fish farmers in Nigeria and urgent solution must be proferred if fish farming is to be attractive, lucrative and sustainable (Madu et al., 2003).
Therefore, it is important to standardize the quality of commercial feed for the target species in aquaculture for optimum production.
1.3 JUSTIFICATION OF THE STUDY
Feed is a vital resource for fish, it is the substance in which the fish depends on for energy required for daily activities and therefore the growth of any fish is directly related and dependent to the quality of the feed (Ajana et al,2006)
Nigeria is currently flooded with many types of commercial pelleted fish feeds from different part of the world to boost aquaculture in the country. Each manufacturer
Claims that his own is the best. These commercial feeds are expensive. Grass root farmers including medium and large scale fish farmers are rather confused as the best ones to patronize. As fisheries experts, it becomes relevant that a study of this nature be carried out on the available commercial fish feeds in order to advise the farmers adequately.
1.4 AIM AND OBJECTIVES OF THE STUDY
The overall objective of this study was to determine through culture study, the best commercial fish feed for the rapid growth and survival of cultured Clarias gariepinus. The specific objectives were: