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During 12 months of sampling, from 17 stations, 327 specimens of Soboor fish Tenualosa ilisha, including 120 females, 113 males and 86 immature were caught. Total length (TL) of the fishes was 120-500mm. Maximum diameters of soboor ova 0.795mm and the ova with diameter more than 0.7 mm released at one spawning round. Temporal and spatial distribution of ova diameter corresponding to GSI changes showed that ova with diameters between 0.64 to 0.795 mm released spontaneously in many rounds along fish migration route during its spawning season. The results indicate that the spawning of soboor begins upon its entering to Bahmanshir and Arvand Rivers on April and continued up to Shushtar and Dezful cities on September where their migration route and season are ended.

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Reproductive biology of three important small indigenous fish species mola (Amblypharyngodon mola), punti (Puntius sophore) and chela (Chela cachius) was studied for 12 months from January to December, 1999 in the Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh. Gonadosomatic index (GSI) and ova diameter were analysed to determine their reproductive cycle. Three hundred sixty female and one hundred forty four male samples of each species of fish, mola (Amblypharyngodon mola), punti (Puntius sophore) and chela (Chela cachius) were examined in this study. The GSI values for female mola, punti and chela ranged from 1.78±0.88 to 17.06±2.66, 1.16±0.64 to 24.81±1.50 and 1.34±0.64 to 10.19±2.17, respectively. The highest values of the GSI in mola and punti were obtained during July while that of chela, during June. The results of monthly observations on the ova diameter indicated that mola, punti and chela spawned at least twice a year, once during May-July and again during September-October.

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Some reproduction characteristics of keeled mullet, Liza klunzingeri, were studied during Apr. 2003 to Feb. 2004 in Khuzestan waters of the Persian Gulf.
A total of 836 samples were monthly collected from two fish landings of Bahrekan and Hendijan; 727 specimens were studied from point of sex determination, and 60 specimens were studied from the fecundity point of view. This species was found to have more abundance in autumn (esp. Oct-Nov). The samples composed of 89 (12.2%) male, 467(64.2%) female and 171 (23.6%) immature; the sex ratio was M:F = 1:5. The advanced stages of maturity (4^th& 5^th) were found in October onward. The highest Gonadosomatic Index was in December and the lowest was in June. The maximum absolute and relative fecundities were 183040 and 2232, respectively; the minimum absolute and relative fecundities were 44700 and 582, respectively. The minimum and maximum egg diameter was 0.04mm (stage 2^nd) and 0.75mm (stage 6^th).

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Some aspects of the reproductive biology of the Indian squid, Uroteuthis duvauceli, were studied from June 2006 to May 2007. A total of 1200 specimens were collected from approximately 30-80m depths by trawling in 50 stations, of which 360 samples were studied for sex determination and fecundity. The minimum and maximum total and mantle length, and body weight were recorded in December and June, respectively. The highest range of total length (410-420mm), mantle length (150-160mm and body weight (90-100g) were encountered in September. The specimens were composed of 34% male and 66% female (M:F=1:2). This species was found to be more abundant in summer. The minimum and maximum ovary weighs were 2.1g and 7.9g with an average of 4.9g, respectively. These values for nidamental gland weight were 0.70 and 2.61g with an average of 1.6g. The minimum and maximum absolute fecundity were 25510 (in August) and 375600 (in April), respectively. These values for relative fecundity were 5207 (in April) and 867 (in August), respectively. The highest gonadosomatic index (GSI) was in April (14.38) and the lowest was in July (8.63). This squid is, therefore, assumed to be a spring spawner. Minimum and maximum egg diameter were 0.72mm (in August) and 2.5mm (in April), respectively.

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Some reproduction characteristics of the Caspian Vimba, Vimba vimba persa, were studied from Oct. 2008 to Sep. 2009 in coastal waters of the Caspian Sea (Mazandaran province). 994 specimens were monthly collected from 6 fish landing sites of Ramsar, Tonekabon, Chalus, Mahmood Abad, Sari and Behshahr. The fecundity was measured using 92 specimens. This species was found to have more abundance in spring (especially April and May). The samples composed of 397(42.6%) male, 537(57.4%) female the sex ratio was M: F = 1:1.35. The advanced stages of maturity (4th & 5th) were found in April and May. The highest Gonadosomatic Index in females was in May and the lowest one was in July. The average of absolute and relative fecundities was 17198±7710 and 171.85±48.8, respectively.

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The aim of the present study was to investigate the reproduction of three species of kilka, including common, anchovy and bigeye kilka in the southeastern waters of Caspian Sea. This study was conducted during 2010 and 6476 specimens were fortnightly collected from fishing landing site. Body weight and fork length were measured. The samples were dissected and female gonads were weighed. Sexual maturity classification was carried out based on six stages in ovarian development. Age was determined using sagitta otoliths. Results were compared with the previous years. Male: Female ratio in common, anchovy and bigeye kilka were 1: 0.779, 0.569: 1 and 0.656: 1, respectively. Study of sexual maturity stages and GSI showed that common kilka spawning began in March and ended in July with the peak in May. Spawning period of anchovy kilka was more extensive than common kilka and take place from April to November with a peak in November. Bigeye kilka spawned during the year entirely. Its spawning occurred intensively during the autumn with a peak in October. Our results showed that M: F ratio differs during the year which is related to their reproduction. The reproduction scheduling of kilka species comparing with the previous years had some changes but has not significantly been affected by the Caspian Sea pelagic changes.

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In this study, the effects of different light regimes on the reproductive activity of a typical Indo- Pacific coral reef rabbitfish, Siganus sutor, were evaluated. Forty- five adult fish were exposed to nine different photoperiod (8L: 16D, 12L: 12D, 16L: 8D) and light intensity (1000, 2000, 3000 lux) combinations with three replicates and five other fishes reared under indoor light condition (Control). Gonadosomatic Index (GSI) and Hepatosomatic Index (HSI) were calculated after 60 days and compared among different experimental regimes in males and females. In the control group, GSI and HSI mean values were 4.67 and 3.24%, respectively, for females and 10.05 and 2.10%, respectively, for males, and these fish showed differences in comparison with the exposed fish. Females kept under 1000 and 2000 lux light intensities had a higher GSI mean value (9.26 and 10.39%, respectively) and also lower average HSI (2.10 and 2.31%, respectively) in 16L: 8D treatment. A similar result was also obtained for males, whereas the 3000 lux light intensity, 8L: 16D day length combination led to more gonadal development (GSIs of 16.41% in females and 12.03% in males). A comparison of results among different photoperiods also confirmed that maturation was induced better in fish maintained under 16L: 8D in both sexes. This investigation revealed the visible role of both photoperiod and light intensity on inducing maturity in the whitespotted rabbitfish, S. sutor. Thus, rearing of adults exposed to an artificial light regime, including 16L: 8D and 2000 lux light intensity, promotes more gonadal development than that occurring in the wild.

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Some aspects of the reproductive biology of Hilsa Shad, Tenualosa ilisha from the Persian Gulf and rivers of Khouzestan Province of Iran were analyzed. A total of 485 fish were sampled by gillnet from landing center of Arvand (AR) and Bahmanshir (BR) rivers during period of April 2010 to September 2010. Reproductive characteristic of T.ilisha showed that sex ratio is M: F=1:2, in PG, AR and BR. This means that females predominate than males. Monthly variations in Gonadosomatic index (GSI) of both sexes were quite apparent. In PG, maximum values were recorded in April for male and female. In AR and BR, maximum values were recorded in June and May for male and female, respectively. Changes in GSI indices are considered as a proof that maturation season in AR and BR is started from March and spawning is started from April to July in AR and BR is started from March to August. The Length - Weight relationship was measured for PG as W= 1.459L2.687, AR and BR as W=2.189L3.166 and W=1.840L2.937, respectively.

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The objective of this study was to contribute to investigate the efficacy of letrozole, a potent non-steroidal aromatase inhibitor, on serum sex steroid levels and oocyte growth in rainbow trout females. Serum steroid levels were measured using an indirect enzyme-linked immunosorbent assay (ELISA) before and 22 days after an initial injection with 1, 2.5 mg kg-1 and subsequent weekly injection with 2.5 mg kg-1letrozole. After the last blood collection, gonad tissues were removed and oocyte diameter and GSI were determined. In all groups treated with letrozole, serum 17β- esteradiol levels (E2) decreased significantly and inversely serum 17α-20ß dihydroxy-4 pregnen- 3- one (17α-20ß-P), testosterone(T) levels increased significantly from 6 to 96 h after injection (p<0.05). The lowest E2 levels, oocyte diameter and GSI were measured in the group treated weekly with 2.5 mg kg-1 letrozole (p<0.05). This study demonstrates that letrozole has the potential to interfere in the synthesis of endogenous estrogens from androgens and delay gonadal development.

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In this study the effect of different protein levels on reproductive performance of Channa striatus was conducted. Snakehead juveniles (65.5±0.2 g) were randomly distributed into nine homogenous groups of 75 fish each. Three isocaloric experimental diets differing in protein levels were prepared. The experiment lasted for 8 months and gonadosomatic index, absolute fecundity, egg diameter, number of mature oocytes, hatching rate, larval length, survival rate and amino acid and proximate composition of tissue, liver and ovary were monitored. Growth, gonadosomatic index (GSI) and absolute fecundity increased with increase in protein level. Protein and lipid content of ovary was highest in fish fed 450 g kg^-1 protein. The percentage of mature oocyte, egg diameter, hatching rate and larval length were the highest in the group fed 450 g kg^-1 protein.  There was no significant difference between the amino acid profiles of muscle tissue in all treatments. Amino acid profile in the liver showed that isoleucine, leusine, phenylalanine and tyrosine were significantly higher in fish fed the 450 g kg ^-1 protein diet.

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