COMPARATIVE GROWTH PERFORMANCE OF AFRICAN CATFISH (Clarias gariepinus) FINGERLINGS OFFERED DIFFERENT TARGET DIETS

ABSTRACT

Aquaculture production is considered the future global solution to declining wild fish capture. However, insufficient production of fish due to lack of affordable quality feeds is a major challenge in aquaculture development. This study investigated the growth performance of fingerlings of African catfish (Clarias gariepinus) fed on experimental diets from sun-dried termites (Macrotermes subhylanus), cockroaches (Periplenata americana), larvae of black soldier fly (Hermetia illucens), desert locusts (Schistocerca gregaria) and polychaetes (Marphysa mossambica) and silver cyprinid (Rastrineobola argentea) as Control diet. Six experimental diets were formulated with three replicates per treatment to contain 40% wheat bran and 60% of sun-dried insects and worms. A total of 720 fingerlings, mean weight 0.362 ± 0.089g were obtained. The experiment was conducted for a period of two months (8 weeks). Water quality parameters were recorded twice a week. The nutritive value of the test diets was determined using Association of Official Analytical Chemists (AOAC) methods. The effect of different diets on specific growth rate (SGR%), survival rate (SR%) and water quality parameters was determined. Correlation analysis was done to determine the relationship between diet and tissue amino acids.

Results indicated that water quality parameters such as temperature, dissolved oxygen and PH were within the acceptable range. The nutritional composition of experimental diets ranged as follows; crude protein: 29.3% – 39.1%, ash: 8.9% – 21.3%, fat: 6.7% – 26.3%, moisture: 6.6% – 11.3%, fibre: 4.7 – 14.2% and carbohydrate: 12.9% – 26.4%. The energy content ranged from 281.1Kcal/100g – 409.5Kcal/100g. The amino acid analyses showed that the experimental diets and fish tissue contained six essential amino acids (histidine, isoleucine, leucine, methionine, phenylalanine, and valine) and six non-essential amino acids (arginine, glutamic acid, hydroxyproline, proline, serine and tyrosine). A highly significant positive correlation was observed between the dietary and the tissue amino acids for both essential and non essential amino acids.

Catfish fingerlings body weight increased progressively throughout the experimental period and was significantly higher at the end of the experiment (Mean= 1.1g) compared to the start of the experiment (Mean= 0.4g). Fingerlings fed on black soldier fly larvae recorded the highest weight gain (401.2%) while fingerlings fed on Polychaetes recorded the lowest (54.2%). No significant variation (P > 0.05) in weight gain was however observed among the fingerlings fed on black soldier fly larvae, cockroach and silver cyprinid (Control diet). The highest specific growth rate was observed on catfish fingerlings fed on black soldier fly larvae (2.64%) and the lowest on fingerlings fed on polychaetes (0.66%). There was no significance difference (P > 0.05) in specific growth rate of fingerlings fed on black soldier fly larvae and silver cyprinid. The survival rates of catfish fingerlings significantly varied among the different diets with the highest survival observed in fingerlings fed on cockroach diet (70.0%) and the lowest in fingerlings fed on termites (9.2%). No significant variation (P > 0.05) in survival rate was observed in fingerlings fed on termites and polychaetes. From this study the diets derived from black soldier fly larvae, cockroaches, desert locusts and silver cyprinid contained the recommended range of nutrients necessary for growth of catfish fingerlings. The findings of this study suggest that black soldier fly larvae, cockroach and desert locust can potentially replace silver cyprinid as protein sources in the culture of African catfish. The aforementioned target organisms are cheaply available throughout the year and can be easily harvested by fish farmers for catfish rearing in ponds.

CHAPTER ONE

 INTRODUCTION 

1.1 Introduction

Aquaculture is an enterprise that is growing rapidly and improving the economy worldwide. Fish are cultivated for food and source of revenue for the growing human population, restocking of streams, lakes, and rivers to curb the shortage due to the decline in the wild capture and for sport fishing (FAO, 2000). Aquaculture aims at production of fish to provide protein in the diet (Sugunan, 2002). Fish is easily digestible, has ability to prevent and manage heart disorders and neurological diseases (Tan et al., 2007).

The global aquaculture fish production rose from 7 percent in 1973 to more than 30 percent in 1997 (Delgado et al., 2003). In 2010, global aquaculture production reached 79 million tons, growing at an annual rate of 9.7 percent since 1998 (FAO, 2012). However, aquaculture global fish production stood at 66.6 million tons in 2012 (FAO, 2014). In 2014, world aquaculture production of fish accounted for 44.1% of total production from capture fisheries and aquaculture up from 42.1% in 2012 (FAO, 2016) and amounted to 73.8 million tons (OECD, 2016). In 2015, global aquaculture production reached 106 million tons, of live weight growing at an average annual rate of 6.6% since 1995 (FAO, 2017a). In sub Saharan Africa, aquaculture growth during 2001-2015 was averaged at 10.4 % (FAO, 2017a).

In Nigeria, over 70% of fish and fish products consumed locally are from wild capture fisheries, principally Lake Victoria. “Fish production has increased over the last decade from 1,012 metric tons produced in 2003 to 21,487 metric tons in 2012” (Munguti et al., 2014). By 2013, Kenya’s total fish production was 152,711, tons of which 23,501 tons came from aquaculture (KNBS, 2014). However, aquaculture production registered a depressed performance with total fish output dropping by 19.8% to 14,952 tons in 2016 from 18,656 tons in 2015 in the country (World Bank, 2017). In Kenya, increasing fish farming is important since it provides a source of income and revenue to farmers and government, improves food security, creates job opportunities to the growing population, and optimizes use of water resource and conservation of biological diversity (Okechi, 2004).

Fish products play an essential role in food security and meeting the nutritional needs of the human population in developing and developed countries (FAO, 2014; Suvitha et al., 2015).

Fish is also an important source of micronutrients such as vitamins, minerals and polyunsaturated omega-3 fatty acids (FAO, 2012). Fish diets with adequate amount of protein are needed for growth, development, survival, reproduction and good health (Suvitha et al., 2015). “Amino acids play an important function as building blocks of proteins and are mainly obtained from proteins in diet and the quality of dietary protein is assessed from essential to nonessential amino acid ratio” (Mohanty et al., 2014; Suvitha et al., 2015). The demand for alternative protein source in fish feed has become more prominent (Sales and Janssens, 2003). “Fish feed is considered good if well accepted by fish, has high digestibility, easily available and is cost effective” (Sogbesan and Ugwumba, 2008). Good quality fish feed should contain all nutritional content supplied in their correct proportions (Wang et al., 2006).

Growth and Feed Conversion Ratio (FCR) are excellent means to figure the suitability of feed in fish feeding experiments (Sahu et al., 2007). “The food conversion ratio (FCR) in fish is 1.5 times better than chicken, lamb or beef” (Menon, 1991). The proceeds from aquaculture are 2 to 5 fold higher than conventional agriculture. However, “Aquaculture in many developing countries has been faced by many challenges” (Osure, 2011). “These include, lack of certified seeds, poor commercially produced feeds, inadequate training programs for farmers and extension workers, inefficiency in dissemination of technology among others” (Mwangi, 2008; Osure, 2011).

The main cost-effective source of protein for fish is plants and animals. Animal proteins are advanced compared to proteins from plants since they have all essential amino acids and are readily digestible but costly. Traditional farmed ingredients have increased the processing of the feeds, hence has influencing success of aquaculture (Kumar, 2000). The aim of formulating good fish feeds is to attain utmost protein deposition and growth within least inputs of feed at a lowest cost. Experimental fish feeds can either be whole or supplemental. Whole diets provide all the nutrients essential for optimum growth and health of fish when reared in bulk in tanks and ponds. Supplemental diets are intended to sustain the ordinary food usually accessible to fish in ponds or outdoor cages. “In fish farming nutrition is critical because feeds represent 50-60% of production cost” (Steven and Helfrich, 2002). The development of natural and traditional aqua feeds like, termites, black soldier fly larvae, desert locusts, cockroaches and polychaetes have been used either as fish bait, wild fish food or supplementary diets in animal feeds (Karuri, 2010) but without much research on their nutritional content. Fish farming management is aims at attaining utmost fish biomass within a specific time frame (Schuchardt et al., 2008).

1.2 Rationale

Competition for protein for fish feeds in aquaculture with human and other livestock needs is a major challenge in the aquaculture industry. The high demand for protein based feeds points to the need for innovative ways of developing quality fish feeds for aquaculture to become tenable. Studies have shown that insects such as termites, desert locusts, cockroaches, black soldier fly larvae, and worms such as polychaetes have high nutritional value in terms of proteins, fatty acids and mineral salts. This study aims at identifying suitable alternative protein source for catfish fingerlings diet from among known insects and worms.

1.3 Objectives and research questions

1.3.1 General objective

To compare the growth performance of catfish fingerlings fed on termites, cockroaches, black soldier fly larvae, desert locusts, polychaetes and silver cyprinid (Control diet) as source of protein in their diets.

1.3.2 Specific Objectives

1. To analyze nutritive composition of target insects (black soldier fly larvae, cockroaches, desert locust, and termites), worms (polychaetes) and silver cyprinid (Control Diet).
2. To determine growth rate of catfish fingerlings (Clarias gariepinus) fed on target experimental diets as source of amino acids.
3. To assess the content of the amino acids in the catfish fingerlings tissue fed on the target experimental diets.

1.3.3 Research questions

1. What is the nutritive value of the target insects (black soldier fly larvae, cockroaches, desert locust, and termites), worms (polychaetes) and silver cyprinid (Control Diet)?
2. What is the growth rate of catfish fingerlings (Clarias gariepinus) fed on target experimental diets as source of amino acids
3. What types of amino acids are present in catfish fingerlings tissue fed on target experimental diets?

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