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 diameter 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.

Capoeta capoeta gracilis (Keyserling, 1891) as a commercial valuable species belongs to cyprinid fish is native to Iran. In this study, the possibility of inducing artificial reproduction of C. Capoeta gracilis was investigated using OvaprimTM hormone. For this purpose, four wild-caught females and one male were selected. Female fish were injected by OvaprimTM at doses of 0. 1 and 0. 4 mg/kg with 12 hours interval. At the time of the second injection, the male fish was injected at a dose of 0. 2 mg/kg. Spawning occurred less than 48 h after the first injection. Maximum and minimum of working fecundity were 2473. 17 and 23430. 5 number. The male fish did not respond to hormone injection and all of the broodstock positively responded to the hormonal induction. These preliminary results revealed that OvaprimTM is a suitable synthetic hormone for reproductive induction in C. capoeta gracilis.

To evaluate spawning status of Vimba vimba, population in Sefid-roud river, 621 breeders, 1136 larvae, tries and fingerlings were caught in the river using beach seine, cast-net and electro-choker over the years 1999-2000. We found that the fish started spawning migration in March and continued it until July with its peak occurring between mid-April to late-May. Fork length was 116 - 208 mm (153.1 ± 17.95) in male specimens and 122 - 222 mm (173.5 ± 16.46) in females. Total body weight ranged 21.1-116.1g (52.92±19.23) in males and 23.1 - 170.0 g (77.90± 22.88) in females. Males aged 2-6 years (3.53±0.86) and females aged 3-7 years (4.l9±0.92) participated in the spawning with their maturity age being calculated as 2 and 3 years respectively. In all, breeders were composed of 51.82% males and 48.18% females with the ratio being significantly different only in May. Gonad weight was 1.13-7.92 g (Avg. 2.89±0.29) in males and 3.21-25.47g (Avg. 10.40±1.52)in females. We found the highest gonad weight for the fish in June and that the gonad weight in female breeders increased upwards of the estuary. Gonado-somatic index was 19-21% in 85.7% of the females and 3-8% in 95.5% of the males. Spawning of the species took place during day and night from late May to late June with its peak in May in water temperature ranging 18-29 degrees centigrade on pebble and gravel grounds from 25 to 75kms away from estuary. The Disaam tributary was distinguished as the major spawning area for the species.

Cytological status of olfactory epithelium during different reproductive phases of Eutropiichthys vacha (Hamilton, 1822) were described by light microscopy. The olfactory organ was composed of various lamella contained two principal layer: olfactory mucosa and central core, radiated from midline raphe. A sharp divergence existed between the mucosa of the olfactory lamella and raphe. The olfactory mucosa was distinguished into sensory and non-sensory epithelium, which consisted of polymorphism of receptors, supporting, labyrinth, mucous and basal cells. The central core was made up of loosely disposed connective tissue, nerve fibres and blood capillaries. A well-developed basement membrane was clearly distinguishable in between the olfactory epithelium and central core. The seasonal changes of the olfactory mucosa during growth, maturation, spawning and post-spawning phases was characterized by considering the tallness and architecture of the receptor cells as main criteria along with commute cellular features and staining patterns of different cell types. The structural components of the olfactory epithelium were correlated with the olfaction in the life of fish concerned.

Adult African catfish (Clarias gariepinus) were used to investigate the effects of prespawning prophylactic disinfection during a seven days quarantine period on the breeding performance and the possible histopathological influences on C. gariepinus brooders. Based on broodfish sex; a total of 36 females were stocked into 6 tanks (6 females tank-1) and 18 males were stoked into other 6 tanks (3 males/tank) signifying three treated groups (T1: T3) of two replicates (6 females+3 males/replicate). T1 was assigned as a control non-treated broodfish, whereas T2 broodfish was disinfected with formalin (FA) (15 ppm) for 6 h and T3 broodfish were disinfected with malachite green (MG) (1 ppm) for 45 minutes. Brooders treated with MG (T3) delivered lower egg numbers, lower hatching percent and high percentage of larval deformity. Additionally, pronounced histopathological lesions were observed in the liver, testis and ovaries of both the FA and MG-treated catfish that is to give a further explanation for the declined breeding performance of both groups. Herein, the pre-spawning disinfection of C. gariepinus during the quarantine period is not necessary especially when proper management, transportation and handling is to be followed. Nevertheless, if prespawning disinfection to be applied; the MG should not be prescribed for C. gariepinus broodfish unless no other cheap and much safer disinfectants rather than FA existed. But still, a future research is required to explore its possible negative effects on both reproductive efficiency and the prospected histopathological changes of broodfish being recovered from FA application.

The histological status of adrenocortical tissues and the correlated seasonal changes in ovarian activities in Mystus vittatus was performed. The tubules and nests of interrenal and chromaffin cells were located in cephalic kidney around the main branches of posterior cardinal vein. Various female germ line cells were identified in the ovary based on size, distinctive features and histoarchitechture of the cells. However, on the basis of relative abundance and size of the different oocytes, the event of oogenesis has been found to occur in four distinct phases, including growth, maturation, spawning and post-spawning. The cytoplasmic features and the architecture of the interrenal and chromaffin cells varied during different phases of the reproductive cycle. During growth and maturation phases, the amount of cytoplasmic granules of interrenal cells increased than chromaffin cells that was in coincidence with the increase of early and late perinucleolar oocytes followed by highest frequency percentage of oocyte at stages IV and V. The cytoplasmic mass of interrenal cells was gradually elevated along with hypertrophied nuclei from the end of maturation and spawning phases also correlated with the increased frequency of mature oocytes. Therefore, gradual accumulation of cytoplasmic granules in the interrenal cells was noticed during post spawning phase. The cytological variations in the interrenal and chromaffin cells harmonized with constitution of different ovarian cells during different reproductive phase in M. vittatus.

The effects of five different food including: blood worm, artemia cyst, artemia mass powder, gammarus mass powder, and ordinary commercial food were studied on Siamese fighting fish (Betta splendens) propagation efficiency during thirty days in a Randomize Totally Design with 4 times repeatition. Experimental plots had been consisted of twenty 30×30×40 (cm) aquarium which a pair of male and female brood stocks were introduced to each one. Male and female fish were separated in each plot by a glass plate for 15 days in order to get prepared for spawning. The results of experiment showed no significant difference on spawned ova, ova diameter, and hatched ova among various ration treatment, but the average of compared factors showed spawned ova, hatched ova, and ova diameter, were better in those brood stocks which had been fed by blood worm food treatment. However, ordinary commercial food treatment had the weakest results through all ration treatments.