In out of the propagation time, the sex cells preparation is so difficult. Thus, the cryopreservation is helped to better investigations and propagation program management quality.  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 frozen automatically by Planner Kryo instrument and placed in liquid nitrogen. The sperm samples were thawed 1 to 3 months after the date of the first freezing and their quality were assessed by measuring percent and timing motility. The results showed significant differences between fresh and frozen/thawed sperm of the Caspian trout regarding motility percent. There were not found a significant difference   in duration of mobility between fresh and frozen/thawed sperm Caspian trout. The results showed a significantly decrease of the motility percent and mobility duration of Caspian kutum frozen/thawed sperm compared with fresh sperm. The results showed that the sample of Caspian kutum sperm that were diluted by ethylene glycol after thawing and were immotile 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.