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The paper presents the results of studies on spined loach, Cobitis taenia (L.) diet in Zegrzyński Dam Reservoir. Food composition of the fish collected at four stations was analysed and compared. The stations differed as to the environmental conditions. Changes of diet components in particular months were described for two sampling stations, habitat conditions preferred by spined loach were described on the basis of the results and the literature data. A description was also given of its feeding grounds in the reservoir, and of the food of this fish in different places of its range of occurrence.
Background. The omnivorous freshwater loach, Lepidocephalichthys guntea (Hamilton, 1822) inhibiting unique ecological niche where oxygen content is low. Its alimentary canal is remarkably short, which is surprising considering the fact that this fish is an omnivore. This peculiarity can be correlated with the specific nature of food. Therefore, the aim of the present study was to investigate the mucosal adaptation of the intestine in adult L. guntea with respective digestive- as well as respiratory function. Materials and Methods. The surface design of the mucosa of different sections (anterior, mid, and posterior) of the intestine of L. guntea were studied using light and scanning electron microscope following commonly accepted procedures. Results. The mucosa of the anterior intestine was provided with various types of mucosal folds and crowded with almost closely oval or rounded columnar epithelial cells with prominent microridges. The irregular mucosal surface of the mid intestine was exemplified by regularly spaced columnar epithelial cells with minute and prominent microridges/microvilli. On the contrary, irregular mucosal folds with stumpy villi were detected in the posterior intestine. The mucosal surface of that region was made up of columnar epithelial cells containing inconspicuous microridges. In that region the submucosa was provided with increasing number of blood vessels. Various cellular elements in the anterior and mid intestine were accordingly adapted to serve the important functions of absorption and gas exchange. However, the arrangement of low mucosal folds and dense blood capillaries in between the folds in the posterior intestine unequivocally suggested its respiratory role. Conclusion. The micro-architectural pattern and cellular architecture of the anterior intestine and middle intestine of L. guntea unequivocally suggests that these two regions are adapted to serve major role of digestion and absorption process. However, major changes that appear in the posterior intestine are considerably reduction of the absorptive area and the penetration of blood capillaries in between the columnar epithelial cells. Therefore, the posterior intestine of L. guntea is probably adapted to suit its role for aerial respiration. However, further investigation is needed the detailed physiological processes involved for aerial respiration in the region concerned.
Laboratory studies were made on the conversion efficiency of food by Noemacheilus montanus (McClelland), abundantly found in high, altitude streams of Garhwal Himalaya. The fish were fed and reared on two types food, viz., natural food (macro- zoobenthos) and commercial fish meal (CFM) in different groups for 30 days. There was no marked difference in the feeding rate of N. montanus fed on natural food and CFM. The specific growth rate was estimated to be 6.34 ±0.30 and 6.68 ±0.11 mg/gm fish/day for natural food and CFM fed groups respectively. The conversion efficiency of the fish reared on CFM was higher in comparison to natural food. A positive correlation was observed between feeding rate and specific growth rate.
Morphological characteristics of M. fossilis was based on 139 specimens. Sexual dimorphism is manifested in 20 metric characters and in anatomical differences: structure of pectoral fins and presence of thickenings on the body sides of males. Growth of particular body parts is allometric, the main increase in the total body length falling on its mid part. Based on literature data, the material was compared with other European populations. The comparison revealed a wide variation of metric characters showing, however, no clinal pattern.
The paper presents the results of studies on meristic and biometric parameters in spined loach, Cobitis taenia (L.) from Zegrzyński Dam Reservoir. Body proportions were determined as well as the relations between the parameters under study and body and head length. Statistically significant differences were found in the values of some biometric parameters m males and females. The results were compared with the ĺata from the lit- erature of spined loach populations in which the species Cobitis taenia was well defined.
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