Housefly Maggot Meal (Magmeal): An Emerging Substitute of Fishmeal in Tilapia Diets

Several feed ingredients have been investigated in an attempt to substitute fishmeal in the diets of fish and livestock. These include both animal protein and plant protein sources. Unfortunately attempts to use these ingredients for complete replacement of the fishmeal component in tilapia diets have not entirely been successful. A major reason is the suboptimal content of essential amino acids in the diets especially methionine. Based on cost effectiveness, availability, crude protein content and amino acid profile, magmeal seem to be a candidate for replacement of fishmeal in fish diets. In this study, seven test diets (36% crude protein, dry matter) formulated by replacing fishmeal with magmeal were fed to triplicate groups of fifteen fingerlings (initial average weight 2.0±0.1g) for 56 days. Results obtained from growth parameters, protein utilisation, stress indicators and haematological parameters revealed no significant difference among all feeding groups. The observation suggests that magmeal can completely replace fishmeal in the diet of Tilapia Oreochromis niloticus fingerling and can meet the nutrient requirements of this species. Introduction Approximately 30% of the total fish catch are converted to fish meal and fish oil for the use in animal and fish feed actually. The percentage of the fish meal used for aquaculture feeds has increased from 10% in 1988 to around 45% in 2002 and the actual amount of fish harvested to produce fish meal has remained constant at 30 million/year (FAO 1999). Aquaculture is likely to grow over the next 20 years and some experts are concerned that rising demand for fish meal and fish oil could place heavier fishing pressure on already threatened stocks of fish used for feed (Delgado et al. 2003). It will also increase the already high cost of fishmeal in the world market. Several attempts have therefore been made to find adequate substitutes for fish meal in fish diets. Unfortunately attempts to use protein sources of plant or animal origin as complete replacements for the fish meal component in fish diets showed varying success. Ogunji (2004) summarised some of the factors which may have contributed to the variation in the results obtained like protein composition and amino acid profile of alternative feeds; apparent digestibility of feeds; phosphorus content of alternative feeds; anti-nutritional factors in alternative feeds (especially in protein sources of plant origin) and palatability/acceptability of alternative feeds. A relatively new approach is the use of insects as a source of animal protein in fish nutrition. Bondari and Sheppard (1981) stressed that insects in various developmental stages have been used to feed fish and farm animals. Hickling (1962) and Kling and Wöhlbier (1974) noted that silkworm pupae have been an important component of carp diet in Japan and China. Newton et al. (1977) used dried ground soldier fly larvae as a dietary supplement for young pigs with success. Interestingly study of the use of housefly maggot meal (magmeal) as substitute for fish meal in fish diets have increased in recent times (Adesulu and Mustapha, 2000; Fasakin et al., 2003; Ajani et al., 2004).