Regarding the role of sex-reversed fish in production of all-female rainbow trout, sperm traits of neomale rainbow trout (treatment 1) were compared with those of normal (XY-male) males. Sperm sample were obtained directly by stripping from normal males (control) or by surgery of testis (treatment 2). Spermatocrit, sperm motility, duration of sperm motility in water and diluent solution, fertilization rate and the percentage of produced normal larvae, were compared. Final results revealed that all assessed traits were identical, expect spermatocrit and sperm motility. There was no difference between spermatocrits from neomales (84%) and those from normal males of treatment 2 (78%), but the spermatocrit from these two groups were higher than spermatocrits from normal males (35.33%) in control. The number of motile spermatozoa from normal males (control) was higher than those from neomales, which was, in turn higher than those of normal males of treatment 2 (P<0.01). Gonadosomatic Index (GSI) assessment results showed that GSI was higher in neomales (P<0.05). The results also suggested that the use of diluent solution led to longer period of sperm motility duration in neomales (P<0.05).

Sperm morphological study on 21 Persian sturgeon (Acipenser persicus) showed that the mid sperm length, sperm width, total length of sperm, sperm density and spermatocrit were 9.48 m, 1.8 m, 62.3 m, 2.92 x 109/ml and 11% respectively and there were significant differences between male characteristics. The statistics showed a significant relationship between sperm density and spermatocrit (r2=78.75). All of the morphological features in this species were greater than the beluga sperm characters. There was no significant relationship between sperm density with flagella length, total length of sperm, fish total length and weight and condition factor in the Persian sturgeon.

In this research, 15 male brood stocks in three age groups of 2+, 3+ and 4+, and 8 female brood stocks were used in order to study the correlation between the spermatocrit and the period of sperm motility as a qualitative indicator, on the one hand, and the fertilization rate and the formation rate of eyed eggs, on the other hand, were used. Five brood stocks were used in each age group. Results of the research showed that correlation between spermatocrit of male brood stocks in the same age group with fertilization rate (r=0.804) and eyed egg (r =0.836) is positive and significant. Correlation between spermatocrit of male brood stocks in one age group and the duration of motility was negative and significant (r=-0.374), and correlation between duration of motility with fertilization rate (r = 0.271) and eyed egg (r = 0.031) was not significant. There was a significant difference in the average spermatocrit of various male age groups (P³0.05) while 2+ years males were the highest (32.66±0.46%) and 3+ years males were lowest (23/26±0/18%) percentage of spermatocrit in this range. 2+ years males showed lowest duration of motility (24.50±0.2 sec), and 4+ years males showed the highest time (27.40±0.14) at (P£0.03). Fertilization rate in 2+ years male were highest (87.52±1.16) and had significant difference as compared to 3+ (79.39±2.2) and 4+ (80.45±2.02) male ages (P£0.031). Eyed eggs in 2+ years male were highest (82.52±1) and had significant difference with others groups while 3+ years males (74.60± 0.8) showed lowest eyed egg rate.

Some biological aspects of bream (Abramis brama) such as seminal plasma indices (ionic and organic composition) and their relationships with sperm motility were investigated. Seminal plasma contained 59.05±8.27 mmol/l Na+, 1.65±0.354 mmol/l K+, 5.95±1.45 mg/dl Ca2+, 18.36±3.46 mEq/l Mg2+, 0.150±0.055g/dl protein, 29.42±7.17 mg/dl cholesterol and 38.11±8.59 mg/dl glucose. Semen spermatocrit was 35.35±8.06%, pH 7.69±0.227 and duration of spermatozoa movement was 56.30±14.18s. The sodium/potassium and calcium/potassium ratios were 35.78 and 3.60, respectively. Spermatazoa in two out of 10 bream semen samples were motile in seminal plasma.There were no significant correlation between ionic and organic composition of the seminal plasma and sperm motility (p>0.05), but there were significant negative correlation between glucose and spermatocrite (r=-0.785, p<0.01).Consequently, although there were no definite correlations between biochemical and spermatological parameters, it was observed that higher spermatocrite content had negative effect on glucose content.

The relationship between morphometric characteristics, motile spermatozoan percentage and sperm motility duration among male breeders of Rutilus frisii kutum in four different rivers (Shirud, Khoshkrud, Sefidrud and Chalevand) of the southwestern part of the Caspian Sea and water osmolarity, pH and temperature in four region of each river (estuary, river entrance to sea, artificial reproduction site and upstream) were considered. The mean motility duration time was 37.2±4.2, 41.4±3.9, 52.9±2.1 and 47.8±3.4 in the four rivers respectively. Also, the percentage of motile cells was found to be 49±4.1, 58.2±6.8, 74±4.8 and 68.1±5.9% for the rivers respectively. The mean osmolarity, temperature and pH were 71.7±66, 62.5±85.5, 40.2±34.2,36.7±34.4 mOsml/l, 14, 15, 13.6±0.2,14oC and 7.6±0.1, 7.2±0.1, 7.4±0.1 and 7.2±0.1 respectively. Our findings showed that there is a positive relationship between motile spermatozoan percentage and duration of motility. With the decrease in river water osmolarity from estuaries up to the river upstream, the motile spermatozoan. percentage and their duration increased. According to anadromous behaviour of the fish, with increasing distance from artificial breeding sites toward river upstream, quantity of spermatozoa and spermatozoan activity increased enhancing success in fertilization attempts.