In the present investigation a total of six parasite species, some eye-specific AND others non-organ specific parasites were found in the eyes of 48 examined fish species, collected from FRESH AND BRACKISH WATERs of Iran during 2004-2006. Ichthyophthirius multifiliis was isolated from the external surface of the eyes of Oncorhynchus mykiss, Gyrodactylus stankovici from Cyprinus carpio AND Lernaea cyprinacea from Cyprinus carpio AND Hypophthalmichthys molitrix. In the vitreous humor parasite species were Tylodelphys clavata (metacercaria) observed in H. molitrix, Alhurnus alburnus, Carassius auratus, Cyprinus carpio, Chondrostoma regium, Ctenopharyngodon idella AND Capoeta capoela, AND Ornithodiplostomum sp. (metacercaria) in Aphanius vladykovi. Diplostomum spathaceum (metacercaria) was found in the lens of eyes of 40 out of 48 fish species. Among parasite species identified, Tylodelphys clavata AND Ornithodiplosrtomum sp. are recorded in Iran for the first time. Additionally, the geographical distribution AND host range of Diploslomum spathaceum metacercaria is also presented in this study.

This paper presents a total of 11 known crustacean parasite species from 51 host species belonging to 7 families, with 17 genera reported from cultured AND wild fishes in three faunal regions of Iran. Among them, one belonging to Branchiura order, namely Argulus foliaceus, was found on Capoeta capoeta in Makoo Reservoir as well as on Cyprinus carpio, Chalcalburnus sp., Hypophthalmichthys molitrix AND Mastacembelus mastacembelus in Zarivar Lake. The other 10 species belonging to Copepoda order include 1) Ergasilus sieboldi, found on the gills of 2) Barbus sharpeyi, B. luteus, Aspius vorax AND Cyprinus carpio; 3) E. peregrinus on Ctenopharyngodon idella AND Leuciscus cephalus in KhANDaqloo Reservoir; 4) Lamproglena compacta AND 5) L. polchella on the gills of infected fish species inhabiting Tigris, Caspian AND Oriental Regions of Iran. 6) Tracheliastes longicollis on the fins of Capoeta capoeta AND Leuciscus cephalus; 7) T. polycolpus on the fins of Capoeta trutta, C. capoeta AND Leuciscus cephalus in WATER bodies situated in Azerbaijan Province (Caspian Region) AND Kurdistan Province (Tigris Region), 8) Achtheres percarum on the skin AND fins of SANDer lucioperca AND Perca fluviatilis in Anzali Lagoon AND Sefid-rud River in North of Iran (Caspian Region); 9) Pseudotracheliastes stellatus on the skin of acipenserids in Caspian Sea AND finally 10) the most economically significant parasite, Lernaea cyprinacea, which is commonly found on cultured cyprinids in ponds AND natural WATER bodies. Furthermore, several unknown crustacean species belong to both orders identified to genus level, which need further study for a detailed description. Geographical distribution as well as host ranges of the mentioned parasites are presented AND discussed.

In this investigation, Rainbow trout fish's growth rate, blood factors were studied in BRACKISH WATER (8.9 ppt) AND FRESH WATER. For doing this research, some 180 young Rainbow trout with a weight of 47.1±0.1 grams were realest in 6 polyethylene tanks with each 1.5m3 WATER. Two treatments with three replicates were used in this study.At the time of testing, all environmental conditions were almost constants similar. Feeding at the time of rearing for every replicate, with due attention to WATER temperature AND fish biomass was done. Every fifteen days the process of biometry of fish was done AND recorded. After 126 days the live fish were transferred to libratory AND after biometry of their weight AND length, all desired blood factors were measured using blood from their hearth. The results of four biometry processes showed that fish growth in BRACKISH WATER was significantly increased (P<0.05). With due attention to other treatments amount of WBC, Hb, HCT, MCV, MCH, MCHC, Lymph, Throm, K+ in BRACKISH WATER showed significant increase as compared with specimens FRESH WATER (P<0.05).Mono, Neut, Eos, Na+ in BRACKISH WATER AND FRESH WATER did not show any significant difference (p>0.05).

In this study, in order to determine the appropriate time AND size to release Salmo trutta caspius, in Kelardasht center conditions, some biometric AND physiological parameters were investigated. In this regard, sampling was carried out twice in each season from Parr (one-summer fingerlings) to smolt (two- summer fingerlings) stages in the course of 1 year. The trend of length, weight AND condition factor, ions, Osmolality, thyroid hormones (T3, T4) AND Cortisol levels of plasma in FRESHWATER fish AND those transferred to Caspian sea BRACKISH WATER were measured. Based on the results, weight AND length of fishes increased significantly from 8 g AND 9.2 cm in autumn to 35.3 g AND 14.9 cm in next summer, respectively (p<0.05). Ions AND Osmolality levels did not show significant differences among different seasons, but after transfer to Caspian Sea WATER a significant increase in ions levels was observed. The lowest AND highest levels of T3 observed in autumn AND summer, respectively, AND difference between these seasons were significant. The highest level of T4 was recorded in spring which was significantly different from that value of autumn. Plasma T4 levels showed significant differences between FRESHWATER AND BRACKISH WATER in autumn. There were no significant differences among different seasons AND FRESH AND BRACKISH WATER, but the least AND highest levels of Cortisol observed in spring AND autumn, respectively. Based on these results, it seems that the fish with 20.9 g weight AND 12.9 cm length in spring has the most appropriate physiological conditions for release.

Ovarian development of rainbow trout of 200 5gr average weight reared for 140 days in FRESH AND BRACKISH WATER was studied. Temperature, pH AND dissolved oxygen in both FRESH AND BRACKISH WATER were the same during the rearing period. The salinities of FRESH AND BRACKISH WATER were 0.4-0.5 AND 14.3-14.7 ppt, respectively.Histological studies indicated that the ovarian development was accelerated in BRACKISH WATER. Hepatosomatic (HSI) AND Gonadosomatic (GSI) Indices also corresponded the ovarian development.

Structure, size AND number of tubules were investigated in kidney of Kutum, Rutilus frisii kutum captured from BRACKISH WATER (Caspian Sea) AND FRESH WATER (Khoshkrood River). 10 mature Kutum were collected from Anzali coast with 8.49 ppt salinity AND 12.4oC temperature. The same number of specimens ware also collected from FRESHWATER with 0.18 ppt salinity AND 18oC temperature. Anterior, middle AND posterior parts of the kidney from each sample were dissected for histological examination. Glomerular distal, proximal AND collecting tubules of kidney were compared in two aquatic habitats. There were no differences in number of kidney tubules. The mean size of glomerular AND collecting tubules were significantly larger in FRESH WATER samples than sea WATER saples (P<0.05). The mean Size of proximal tubules was marginally larger in seaWATER compared to FRESHWATER, although such difference was not significant.

In this experiment for study of growth performance of rainbow trout in two kinds of WATERs, two groups of juvenile rainbow trout (Oncorhynchus mykis) with the mean weight of 29.1±3.37 g were cultured in BRACKISH WATER treatment with salinity of 2.950 PPt. AND FRESH WATER with 0.57 PPt. for 40 days respectively. Each treatment was conducted in triplicates (245 rainbow Trout fish). At the termination of experiment, the obtained data were analyzed in t-test experiment. The results showed that growth AND feeding performance of Raibow trout in BRACKISH WATER was increased AND had significant difference (P<0.05) in comparison with FRESH WATER. The final body weight AND final body length of Raibow trout fish (82.69±5.3 g, 19.1±2.6 cm) in brakish WATER treatment had significant difference (P<0.05) in comparison with FRESH WATER treatment (69.2±7.5 g AND 17.6±3.1 cm) (P<0.05).Also in BRACKISH WATER treatment, the parameters of daily growth coefficient, specific growth rate of length, velocity of length AND velocity of weight in comparison with FRESH WATER treatment was significantly increased (P<0.05). The lowest food conversion ratio (1.6), highest protein efficiency ratio (1.8) AND lipid efficiency ratio (7.7) were obtained in BRACKISH WATER treatment AND showed significant difference (P<0.05) with FRESH WATER. The present study showed that rainbow trout had a good ability of growth in BRACKISH WATER in comparison with FRESH WATER AND growth performance of this fish in brakish WATER is higher.

The study was carried out to evaluate the effects of varying stocking densities on the growth performance AND nutrition indices on Huso huso fingerlings during the acclimation to the formulated diet. This study was conducted in two phases. In the first phase of study, 252 Huso huso with the mean weight of 3.3±1.9 g (Mean±SD) were stocked in two different conditions (FRESH WATER AND BRACKISH WATER) at three different stocking densities. The stocking densities were 150 (n=42), 250 (n=78) AND 450 (n=132) g/m2 in the first phase. In the second phase of experiment, 522 Huso huso (5.9±1.1 g) (Mean±SD) were reared at 500 (n=84), 1000 (n=168) AND 1500 (n=270) g/m2 stocking densities. The adaptation period to the formulated diet was 20 days. Results showed that the highest growth was recorded in H. huso stocked at 1000 g m-2 in BRACKISH WATER which was significantly higher (P<0.5) than that recorded in FRESHWATER suggesting the advantage of rearing H. huso in BRACKISH WATER at improved density of 1000 g m-2. Results obtained from total length in juvenile H. huso conform to these results. Low specific growth rate (SGR) was reported with a stocking density of 1500 g m-2 in FRESHWATER which was not significantly different from that in BRACKISH WATER. Hence rearing juvenile H. huso in BRACKISH WATER at high densities (1500 g m-2) is preferred to rearing in FRESHWATER as H. huso is more capable of adapting to stressful conditions of stocking density in BRACKISH WATER. Similar trends were observed for percentage body weight increase (BWI%) showing the advantage of using a stocking density of 1000 g m-2 in BRACKISH WATER. According to the results of this study, Huso huso with a mean weight of 3-5 g can feed on dry formulated diet completely during a period of 20 days.

Rainbow trout (Oncorhynchus mykiss) weighting 200±5 grams were used in this study to compare their gonad development in FRESH AND BRACKISH WATER in Yazd Province. The culture period lasted 140 days from October to March 2003 during which time the temperature (13.8±0.6), pH (8.18±0.12) AND dissolved oxygen (6.2±0.11) of FRESH AND BRACKISH WATER were kept nearly constant. The salinity of FRESH AND BRACKISH WATER was 0.4-0.5 AND 14.3­-14.7ppt respectively. The fish were fed common commercial trout food (Chineh GFT2) based on temperature AND biomass.Histological studies indicated that the gonad development is accelerated in BRACKISH WATER where the males mature two month earlier than those reared in FRESHWATER. The gonadosomatic index (GSI) also affirmed the gonad development (P<0.05).

Experiment was conducted for 8 weeks to determine the reaction (Astacus leptodactylus) to interaction energy AND salinity. Diets containing 3 levels of energy (300, 370 AND 450 kcal/100g) with a constant protein content of 30% AND 2 levels of salinity (FRESH WATER AND BRACKISH WATER (12 ppt) were formulated. Tank content 110 liter, each filled with 80 liter WATER.5 A.leptodactylus(average weight of 17±2) were storage per each tank AND feed twice a day. Results showed different levels of energy did not have significant effect on growth factor AND survival of crayfish (P<0.05), but FRESH WATER AND BRACKISH WATER had a significant effect on growth factor. The best growth was seen in FRESH WATER. Survey on interaction between energy –salinity was indicated the highest growth were seen in (FRESH WATER) AND energy 370 (kcal/100g).Caracas analyzes (protein AND lipid) in treatment salinity decreased AND has a significant (P<0.05) effect. The highest protein carcass was seen in interaction between energy (370 kcal/100gr) AND (0 ppt) which had significantly different with other treatments (P<0.05). The greatest amount protein of body composition were in practical diet containing 370 kcal/100gr energy AND FRESH WATER which had significantly differences with other treatment (P<0.05). Overall this study indicates the dietary which containing 370 kcal/100gr energy in FRESH WATER has the greatest performance on growth, nutrition AND body composition.