Practical diet formulation for common carp (Cyprinus carpio) and walking catfish (Clarias macrocephalus) larvae in Thailand

There is a need for the development of formulated diets for fish larvae. The present study was conducted in Thailand on common carp (Cyprinus carpio) and walking catfish (Clarias macrocephalus) larvae with the following objectives: 1) To assess the nutritive values of several available feed ingredients when used singly or in different combinations; 2) To formulate a cost effective practical diet, using locally available ingredients, to replace live foods in larval culture; 3) To determine the relative suitability of dry or moist forms of diets under conditions of local climate. Live Artemia nauplii, Moina, and practical diets formulated by the National Inland Fisheries Institute (NIFI),Thailand were used as reference diets for assessing the performance of fish fed the experimental diets. Dietary particles size was adjusted to 125-250 pirn after measurements of the larval mouth size between 13-18 days of age. Feeding trials were conducted using many combinations of available ingredients and performance of the larvae was based upon food acceptance, survival, and growth in length. Four diets: a moist and a dry diet of the experimental diets that had given superior performance, Artemia nauplii, and the NIFI 1 diet were used in a final feeding trial conducted on 1000 common carp larvae. The moist diet (now called Burirum 1) had the following proximate analysis on dry weight basis: 40.4% crude protein, 15.6% crude fat,33.4% carbohydrate including fiber and 10.7% ash; and composition: 16.3% raw pork liver,8.1% coagulated cooked chicken diet, 16.3% whole chicken egg, 16.3% raw squid meal, 26% frozen Artemia, 0.8% cooked peanut, 1.5% corn oil, 4.1% skim milk, a vitamin-mineral supplement, 2% K-carrageenan. The four diets were not significantly different with respect to their effects on larval survival. Mean survival was 67.7%. Larval body length responses for Artemia nauplii., the moist diet, the dry diet and the NIFI 1 diet were 9.1, 8.9, 8.4 and 8.2 mm, respectively. Dissolved oxygen, alkalinity and water hardness were 8 mg/1, 620 ppm and 880 ppm. The water temperature in the rearing tanks ranged from25-29°C and water pH was 7.65. Three feeding trials with moist diets and four with dry diets were conducted on walking catfish larvae. Four diets: a moist and a dry diet that had given superior performance, Artemia nauplii, and the NIFI 2 diet were used in a final feeding trial conducted on 1000 walking catfish larvae. Proximate analysis on dry weight basis of the dry diet (now called Burirum 2) was: 39.8% crude protein, 9.4% crude fat, 15.4%carbohydrate including fiber and 35.3% ash, and its composition was: 60% fish meal, 7.9%corn meal, 9.8% peanut meal, 7.9% rice bran, 4.6% corn oil with vitamin-mineral premix added. Larval body length and survival indicated significantly different responses to the diets. Survival rates for Artemia nauplii, the dry diet, the NIFI 2 diet and the moist diet were 65.6, 62.8, 56.3 and 48.5%, respectively. Body lengths in response to Artemia nauplii, the moist diet, the dry diet and the NIFI 2 were 12.5, 12.0, 12.0 and 10.8 mm, respectively. It is concluded that appropriately formulated practical diets can satisfactorily replace live foods in larval culture of common carp and walking catfish. The moist diet was more effective than the dry diet for common carp larvae whereas the dry diet was more effective than the moist diet for walking catfish larvae.Land and Food Systems, Faculty ofGraduat