در رودخانه زرين گل استان گلستان Nemacheilus malapterurus مطالعه برخي از ويژگي هاي زيست شناختي

A Study of Some Biological Aspects of Nemacheilus malapterurus, Zarringol River, Golestan Province

This study was conducted to determine some of the biological aspects, namely weight, total length, relative gut length (RLG/Index), growth, condition factor, food habits and food selectivity of river loaches, Nemacheilus malapterurus, in Zarringol river, Golestan province, northern Iran. A total of 149 specimens were caught using an Electro-shocker and immediately fixed in 10% formalin. The frequency for males, females and immature was 37.5, 9.3 and 35.5% respectively. Sex ratio was 4:1(male: female). Statistical means for total length and body weight were significantly different for males and females (P<0.01). Average total length and body weights were 59.07(14.8); 82.42(28.86); 39.73(6.27) mm; and 1.89(1.8); 5.31(4.98); 0.53(0.21) g for males, females and immature, respectively. Condition factor was 2.6 for females and 1.97 for males. The regression coefficient for males and females is less than 3 indicating the length to weight growth to be allometric. The low RLG index (RLG<1) shows that N.malapterurus is carnivore. In this study food selectivity (lvlev Index) was mainly for family Blood worm (Chironomidae) with a frequency of 65.3% in the diet.