Creation of cryopreservation bank of bony fish

In this study, 11 male of Caspian trout (Salmo truta caspius) (with mean length and weight 37/8 ± 5/3 cm and 523/3 ± 24/7 respectively) and 23 male of Caspian kutum (Rutilus frisii kutum) (with mean length and weight 36/1 ± 7/1 cm and 631/3 ± 21/6 g respectively) were evaluated. All the fish were good at the initial examination of sexual maturity. After sperm sampling, their quality were tested. In this step, the parameters such as motility, duration of mobility, density, pH and osmolality were measured. After this stage, the sperm samples of Caspian trout in the ratio 1: 3 were diluted with the aqueous solution containing compounds (0.3M Glucose, 10% Methanol, 10% egg yolk) and the freezing process was done manually and the sperm was frozen in liquid nitrogen. The sperm samples of Caspian kutums were diluted (ratio of 1: 3) with two soluble diluent containing compounds (350 mM glucose, 30 mM Tris and 4% Polyethylene glycol) and (350 mM glucose, 30 mM Tris and 2% Glycerol) and were frizzed automatically by Planner Kryo instrument and placed in liquid nitrogen. The sperm samples were thawed 1 to 3 months after the date of first freezing and their quality were assessed by measuring percent and timing motility. The results showed that the obtained semen volume of Caspian trout was more than Caspian kutum. Moreover, percentage of motile sperm, timing motility and sperm density of Caspian trout were higher than those of Caspian kutum but osmolality and pH of Caspian trout were lower than those of Caspian kutum. Over time, the percentage of sperm motility and mobility for both species declined compared with fresh samples. After thawing, percentage of motile sperm and timing motility of Caspian kutum were lower than those factors Caspian trout. The results showed that the sample of Caspian kutum sperm that were diluted by ethylene glycol after thawing and were immotile ll of them. However, the samples were diluted by glycerol, after thawing, were alive and motile. According to the results, it seems very important species differences that must be fully considered in the process of freezing sperm. The use of a single protocol would not be successful in cryopreservation because the reaction of sperm against to chemical agents is variable. Therefore, it is essential to get the right information to protect valuable Caspian fish by using cryopreservation. Further studies on the characteristics of each species, as well as the freezing process take appropriate diluent