| Nutritional requirements and digestive enzymes of ricefield eel (Monopterus ablus) were studied thoroughly in this paper. The main results and conclusion summarized as follows:l.Food compositions of M.albus were investigated in areas of three counties in Hubei province. Diets of the M.albus with body length less than 100mm change with their growth: from Rotifera and Cladocera to Oligochaeta and Chironomidae. However, the food composition of the M.albus with body length more than 100mm were quite consistent, with Chironomidae, Oligochaeta, Pheretima, Cladocera, Copepoda and insect larvae as the major food items. However, Phytoplanktons, benthic algae and organic debris were also found in intestines of the fish, indicating to some extent that the species is omnivorous.2.The L9(34)table of orthogonal design method was used to formulate nine diet combinations, which were employed to determine the requirements of protein, fat, mineral and general energy for M.albus. The results indicate that protein and general energy are the major elements that affect the growth of the species. The optimum content of protein, fat, mineral and carbohydrate in diets are 35.7%, 3%-4% , 3% and 24%-33% respectively. In the diets of the species, the optimum energy-protein ratio (E/P=KJ/g) is 31.6-38.9.3. Effects of supplement of choline to the diets on the growth, lipid content in liver and index of liver-bodyweight of M. albus were studied. The results show that the growth rate of M. albus feeding on diets without choline is slower, and its feed coeffcient , lipid content in liver and index of liver -body weight are higher than that fed on diets with choline. With the increase of choline content in the diets, its growth rate increase , the feed coefficient, lipid content in liver and the index of liver-bodyweight decrease. When M. albus fed onthe diets with choline content being 0.8%-1.2%, its growth rate, the feed coefficient , lipid content in liver and the index of liver-body weight were close to that fed on animal diets. This shows that proper supplement of choline to the diets is 0.8%-1.2%.4.Effects of supplement of betaine to the diets on the growth , lipid content in liver, index of liver-bodyweight of M. alb us were studied. The results show that the growth rate of M. albus feeding on the diets without betaine is slower, and its feed coefficient, lipid content in liver and index of liver-bodyweight were higher than that feeding on the diets with betaine. With the increase of betaine content in the diets, its growth rate increase, the feed coefficient, lipid content in liver and the index of liver-bodyweight decrease. When M. albus fed on the diets with betaine content being 1.5%-2.0%, its growth rate, the feed coefficient, lipid content in liver and the index t)f liver-bodyweight are close to that fed on animal diets. This shows that the proper supplement of betaine to the diets is 1.5%-2.0% .5. Effects of supplement of Gly. Ala. Phe. Lys. Tyr. betaine and aroma matter to the diets on feeding of M. albus were studied, the appropriate supplement of these matter to the diets can promote the species to feed. For attracting the species to intake formulated diets, the proper content of Gly. Ala. Phe. Tyr. in the diets are 2.0%-5.0%,and Phe 1.0%, betaine 2.0%. aroma matter 5.0%, respectively. The combination of amino acids and combination of amino acids with betaine and aroma matter can improve feeding attraction activities.6.Three formulated diets in accordance with the nutritional requirements of M. albus were employed to feed the species, and the results follows: growth rate and survival rate of the species that feed on the formulated diets are close to that feed on animal diets, the feed coefficient of the formulated diets are 1.6, lower than the feed coefficient of the animal diets. It is suggested that artificial formulated diet can be employed in the culture of M. albus.7.The distribution of activities of protease, trypsin. amylase and lipase in digestive tissues or organs of M.albus are studied.
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