Effect of fluctation temperature on Weight- length and condition factors of Schizothorax pelzami (Kessler,1870) in two habitat lake and river

In order to evaluate aspects of the fluctation temperature on Weight- length and condition factors of Schizothorax pelzami (Kessler،1870) in the two different habitat such as the ferizi River basin and cheshme sabz lake in khorasan province، total of 873 samples were taken monthly from January، 2009 through January، 2010، by means of gill nets. The results showed that lake population was significantly larger and weightier than river population (by T - test (P<0. 001)). This may be due to better environmental conditions and food supply in lake habitat. This relation (Wt-Lt) was evaluated for all individuals، and for each sex separately (females and males)، due to the significant difference between the male and female slopes of Wt-Lt regressions in both ecosystem. Result (Parameter b) showed that Weight increased Isometrically with size in both population but in river females & lake males growth were positive allometrically، (b= 3. 102، b= 3. 107) also river males population and lake females population growth were negative allometrically، (b=2. 807،b=2. 828). In addition Body weight exponentially increased with SL (mm) by the following relationships: River population: W = 0. 21 × 10-4 TL2. 80 (r2 = 0. 93) for males and W = 0. 5 × 10-5 TL 3. 102 (r2 = 0. 96) for females. lake population: W = 0. 5 × 10-5 TL3. 107 (r2 = 0. 93) for males and W = 0. 21 ×10- 4 TL 2. 82 (r2 = 0. 96) for females.