Study On The Growth, Feeding Habits, Digestive System And Nutritional Composition Of Creteuchiloglanis Macropterus

Creteuchiloglanis macropterus belongs to Osteichthyes, Siluriformes, Sisoridae and Creteuchiloglanis. Distribution:Nu-jiang and Irrawaddy river drainages. Specimens were collected from Nu-jiang, Binlang-jiang and Longchuan-jiang from November 2013 to November 2014. The paper studies on the age, growth, feeding habits, digestive system and nutrition composition of Creteuchiloglanis macropterus. The main results are as follows:1. Pectoral spines were used to estimate the age by using simplified decalcified histological sections. Reader agreement for ages compared between pectoral spines and vertebra was 86.36%. Pectoral spines could be used for estimating the age efficiently.2. The sex ratio ((?)) was 1.5:1. The age structure of C. macropterus populations was from 1 to 9, the individuals of the preponderant age groups were 1 to 3, the total length ranged from 60 to 182 mm, preponderant groups was 60 to 110 mm, the body weight ranged from 2.5 to 66.0 g, preponderant groups was less than 20 g. The age structure of females ranged from 1 to 9, the total length ranged from 60 to 182 mm and the body weight ranged from 2.5 to 66.0 g. The age structure of males ranged from 1 to 7, the total length ranged from 62 to 153 mm and the body weight ranged from 2.5 to 34.9 g.3. The females and males showed similar growth patterns, the body weight and total length data fitted the function W=1E-4L24807 (R2=0.8189 n= 180). The relationship between the radius of pectoral spines (Rc) and total length was L=2.0787· RC0.6273 (R2=0.8866 n=180). The Von Bertalanffy growth function for C. macropterus was described as:Lt= 377.015·[1-e-0.0491(t+40195)], W,=246.134·[1 e-0.0491(t+4.0195)]2.4807 Von Bertalanffy parameters were L∞= 377.015 mm, W∞= 246.134 g. The age inflexion point for growth was 14.48, corresponding total length and body weight was 225.00 mm and 68.40 g.4. C. macropterus belongs to zoobenthivores. Larva of aquatic insect was the main foods for C. macropterus, especially Diptera, Trichoptera and Ephemeroptera. F% of Diptera in winter was higher than spring and autumn, F% of Trichoptera and Ephemeroptera in spring and autumn were higher than winter. N% of Diptera in spring was the lowest, but Trichoptera and Ephemeroptera were the highest. Feeding rate in spring was the highest, mean fullness in spring and winter were higher than autumn. As C. macropterus grows, F% and N% of Diptera and Ephemeroptera reduces, while the rate of Trichoptera rises. The feeding intensity of total length groups< 90 and> 120 mm were higher than 90-120 mm. There was high food overlaps for C. macropterus with different season and total length groups.5. The mouth of C. Macropterus was inferior, with developed oral teeth in the large buccal-pharynx cavity and sparse gill raker. The esophagus was short and thick, with developed muscular layers and abundant goblet cells in the mucous layer. The stomach shaped as U, which was composed of cardia, blind sac and pylorus, and lots of gastric glands were observed there. The average intestinal coefficient of the C. macropterus was 0.93, and there had a significant linear correlation between intestine length and standard body length. The intestine could be divided into three sections, including cranial, middle and distal parts, and numerous villi were there. Liver and pancreas were separate, and the former was divided into two lobes. What’s more, exo-coeliac liver was found in this fish, and its pancreatic tissue scattered diffusely in the mucosal lining of the cranial and middle intestine.6. The results showed that the flesh ratio of C. macropterus averaged 70.09%. The content of moisture, protein, fat and ash in fresh muscle were 78.31%,19.29%,1.19% and 1.21%. There were 18 kinds of amino acids in the muscle and the total amount was 87.77%(dry weight), of which 8 essential amino acids for human was 29.37%. Component ratio of essential amino acids accorded with FAO/WHO. EAAI index was 71.72. The percentage of sweet amino acids, bitter amino acids, sour amino acids and umami amino acids were 42.70%,30.69%,25.87% and 23.79%(dry weight). Fourteen kinds of fatty acids were detected in the muscle and the total amount was 3.99%(dry weight). The relative content of SFA, MUFA and PUFA were 33.85%,25.00% and 41.15%, respectively. The IA and IT of fatty acids were 0.48 and 0.28. C. macropterus was rich in minerals.