An investigation on fish parasites in Hanna Wetland, Semirom, Isfahan Province

As a part of a major ecological study of Hanna Wetland, Semirum Region, Isfahan Province, parasitic infestation of 3 native and one introduced fish species were investigated. A total of 120 fish specimens were collected by both cast net and a series of gillnets between fall and winter 2007, and spring and summer 2008. Some of the observed parasites are reported for the first time as new host records of: Trichodina perforata on gill and skin of Carassius auratus auratus and three species of leeches namely: Glossiphonia heteroclite, Thromyzon tessulatum and Hemiclepsis marginata on the skin and fin bases of Capoeta damascina. Moreover, 14 internal and external parasites including: one protozoan; Ichthyophthirius multifiliis and two myxosporeans; Myxobolus varicorhini, Myxobolus sp., three monogeneans; Dactylogyrus lenkoran, Dactylogyrus intermedius and Gyrodactylus sp., two immature digeneans; Diplostomum spathaceum, Tylodephys sp., two mature digeneans; Allocreadium isoporum and A. layman, one unknown cyst, one Acanthocephalan; Acanthocephalorhynchoides sp., one cestoda; Khawia armeniaca. The highest prevalence of Diplostomum spathaceum (100%) was observed in Aphanius isfahanensis and Alburnus sp. However, the lowest prevalence was related to A. layman in Capoeta damascina in winter (0%), and autumn and spring (11%). Leeches infections were only observed in Capoeta damascina and Alburnus sp. in winter and summer, respectively. The maximum average (±SD) infection intensity belonged to K. armeniaca in intestine of C. damascina in spring (12.50±3.40, range: 8-16). Among the parasites identified in the region, D. spathaceum showed the highest mean (±SD) abundance (41.67±11.79) in C. auratus auratus in spring. In general, a relatively high diversity of fish parasitic fauna exists in this water body which could jeopardize fish populations and the whole ecosystem if the ecological status of the Hanna Wetland is neglected

Determination of CPUA and distribution pattern of families Haemulidae, Nemipteridae and Ariidae in the Oman Sea

This trawl survey was carried out during 2013 for the stock assessment of families Haemulids, Nemipterids and Ariids in the Oman Sea. Sampling was carried out at five different stratum and depths. The highest value of CPUA of Haemulidae was estimated for Pomadasys stridens in “B” stratum (885.78 kg nm^-2), for Pomadasys kaakan at depths of 10-20 m (330.35 kg nm^-2), and for Nemipteridae it was estimated for Nemipterus japonicus in “D” stratum (1042.31 kg nm^-2) at 30-50 m depths (1734.97 kg nm^-2), and for Ariidae, it was estimated for Netuma thalassina in the stratum B (752.64 kg nm^-2) at 20-30 m depths (428.33 kg nm^-2). The highest biomass for Haemulidae was estimated in stratum B (320.53 ton) at 50-100 m depths (282.98 tons), and for Nemipteridae in “D” stratum (559.72 tons) and at depths of 30-50 m (604.04 tons), and for Ariidae it was estimated in “B” stratum (272.35 tons) and at 50-100 m depths (255.12 ton). Based on the results obtained, the highest species diversity for Haemulids was in “A” stratum at depths less than 50 m, while for Nemipterids it was similar in the total study area and different depth layers. Highest species diversity for Ariids were found in “A” and “D” strata at depth layers of 10-20 m and 30-50 m, respectively. In light of the fact that fishing efforts decreased during these years, our results illustrate that CPUA and biomass have ascending trends which indicate the relative stability of the stocks of these families

The sub-lethal effects of cadmium on some gill histopathology in the cultivated Sterlet (Acipenser ruthenus)

The sub-lethal effects of water-born Cadmium (Cd) on histopathological changes of gill tissues were investigated on Sterlet, Acipenser ruthenus. In this research, 60 fish (41.69 ± 0.95 g and 23.98 ± 0.14 cm) were randomly distributed in 4 experimental groups, each with 3 replicates. The fish were exposed to different concentrations of Cd for 21 days under semistatic experimental condition as: 0, 16, 32 and 64 µg/L Cd. At the end of the experiment, the gill tissues were fixed in Bouin's solution for histopathological studies. Qualitative and quantitative changes of the gill tissues were analyzed. Several qualitative changes including hyperplasia, hypertrophy of epithelial cells and epithelial edema as well as necrosis, rings and fusion of gill filaments and secondary lamellae were observed in all treated fish including control group. Quantitative analysis based on organ index (Iorg) showed significant increase in histopathological changes in the gill tissues coincided by elevation of Cd concentration in the water. However, there was no significant differences in the organ index between control and 16Cd group.The results of this study demonstrate severe histopathological changes in the gill tissues after exposing to sub-lethal concentration of water-born Cd under experimental condition. The results of this study might be used as a guildline for evaluation of histopahological changes being induced by heavy metals in natural or cultivated environment for sturgeon fish

Age, growth and reproduction of Chondrostoma regium (Heckel, 1843) from the Zayandeh Roud River, Iran

Age, growth and reproduction were investigated for Chondrostoma regium, collected monthly (November 2007- August 2008) from the Dimeh Spring region, Zayandeh Roud River, Iran. The maximum age of collected female and male fish were estimated based on scale increments as five and four years respectively. Von Bertalanffy growth equations were calculated as Lt=246[1-e^-0.206(t-0.034)], Wt=163.29[1-e^-0.206(t-0.034)]^2.77 for females and Lt=253.1[1-e^-0.206(t-0.175)], Wt=188.25[1-e^-0.206(t-0.175)]^2.99 for males. Size ranges of the male and female specimens were almost similar. The fork length range for females was 10.5-18.0 cm and 10.7-19.7 cm for males; and the weight range was 15.7-85.4 g in females, and 14.5-88.5 g in males. The female-male ratio was 1.8:1 (p<0.05), and for both sexes gonadal development and sexual maturity occurred in the second year of their life. Length-weight relationships revealed isometric growth pattern for males and a negative allometric growth for females. Monthly data of Gonadosomatic Index, and ovary condition suggested that spawning occurred during May and June. The mean absolute and relative fecundity was calculated as 2429±1512 (eggs/female) and 78.1±18.7 (egg/g), respectively, and fecundity was significantly correlated with both body weight (r^2=0.90) and fork length (r^2=0.84)

Nutritional value of freshwater mesozooplankton assemblages from Hanna Dam Lake, Iran, during a one-year study

Nutritional value of freshwater mesozooplankton, fatty acid (FA) and amino acid (AA) compositions were determined in the middle of each season for a one-year period from May 2009 to February 2010 in Hanna Dam Lake, Isfahan, Iran. FA and AA composition significantly (P<0.05) varied in relation to the seasonal changes of water quality, phytoplankton and zooplankton community. The content of saturated fatty acids (SAFA), mono unsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) ranged from 22.4-29.0%, 30.9-40.4%, 11.8-20.9% of dry weight (DW), respectively. The major SAFA were 16:0 (13.7-17.0 % DW) and 18:0 (4.9-7.0 % DW), whereas contents of MUFA were mainly 18:1n-9 (13.8-16.2 % DW), 16:1n-7 (6.9-13.6% DW), and 18:1n-7 (5.7-10.6% DW). The major PUFA were 18:2n-6 (2.6-11.7 % DW), 18:3n-3 (2.4-3.1% DW), 20:5n-3 (3.9-4.8% DW), 22:6n-3 (0.73-0.99% DW), and 20:4n-6 (0.56-0.73% DW). As for the ratios of n-3:n-6, the values were 0.70:1, 2.54:1, 2.10:1, and 1.73:1 in spring, summer, autumn and winter respectively. The mean essential amino acid (EAA) and non-essential amino acid (NEAA) were 28.7 and 71.3 %; 31.0 and 69.0 %; 31.63 and 68.4 %; 34.5 and 67.0 % of total amino acid in spring, summer, autumn and winter, respectively. The amount of tyrosin, isolucine, lucine, arginine, cysteine, aspartic acid, glycine and proline were higher in mesozooplankton population at summer and autumn compared to winter and spring

Gut contents study of white leg (Litopenaeus vannamei) shrimp during a culture period from earthen ponds in Delvar of Bushehr

In this research, gut contents of white leg shrimp Litopenaeus vannamei were investigated for 113 days culture period at earthen ponds in Delvar of Bushehr, by sampling every 15 days. Results showed that artificial food had highest weight percentage in gut contents (foregut, midgut, and hindgut) following in order by detritus, zooplankton, phytoplankton, and macrobenthic. In the beginning of culture period, macro-bentic were observed in larval gut contents while other food items were throughout culture period. The maximum occurrence of detritus in gut contents was at 26 and 40 days-old larvae while highest phytoplankton was obtained at 86-days-old larvae in end of culture period. The zooplankton had approximately similar amounts throughout culture period in different parts of gut, while macro-benthic only observed at 26-old-days larvae with maximum amount at foregut and midgut. The mean highest gut fullness attained at foregut (0.95 %) and lowest at hindgut (0.20 %). The dominant color of gut content was green-brown in all parts of gut that could be due to consumption of natural pond products. This study illustrated that most consumed food items in L. vannamei was prepared by natural pond foods. In addition, detritus and plankton have most important in L. vannamei during culture period

Effect of dietary canola oil level on the growth performance and fatty acid composition of fingerlings of rainbow trout (Oncorhynchus mykiss)

This study evaluated the suitability of canola oil as a source of supplemental dietary lipid for rainbow trout. Triplicate groups of the 30 fingerlings held under identical culture conditions were fed twice daily by iso-nitrogenous, iso-calorific and iso-lipidic diets for eight weeks. Experimental diets consisted of 30.3% protein, 18.7 kJg^-1 energy and 16.7% lipid from fish oil (FO), canola oil (CO) and 1:1 blend of the two oils (FCO). Moisture, ash, protein, lipid, final body weight, condition factor, feed conversion ratio, survival and hepatosomatic indices were not affected by treatments. Specific growth rate and weight gain of fish reared on fish oil diet (FOD) and canola oil diet (COD) were significantly higher than those fed with the fish and canola oils diet (FCOD). Protein efficiency ratio was highest in fish fed with the COD. Whole body fatty acid compositions mirrored those of diet treatments. The highest amounts of HUFAs were detected in fish fed with FOD, which was significantly different from other treatments. In all treatments PUFAs/SFAs and n-6/n-3 ratios were higher than 0.45 and lower than 4, respectively. Our results indicate the fingerlings can be reared on diets in which FO has been replaced with CO, with no significant effects on fish growth performance

Growth and reproductive characteristics of Squalius Lepidus Heckel 1843 in the Dimeh spring of Zayandeh-Rud River

Population structure, growth, and reproductive characteristics of Kavar, Squalius lepidus, a native species of Cyprinidae family in Zayandeh-Rud River were investigated by monthly sampling from October 2006 to August 2007. A total of 415 individuals were collected. Age groups of males and females ranged between 1+ and 4+ . The male:female sex ratio was 1:3. The largest female was 163.0mm in fork length and 63.71g in weight; whereas the largest male was 156.0mm in fork length and 50.45g in weight. The minimum, maximum, and mean absolute fecundity was 1161, 12953, and 4279±2169, respectively, and relative fecundity was 148.4±49.3 eggs/g of body weight. Gonadostomatic Index (GSI) values suggested that spawning of Squalius lepidus occurs from May to June. Thus, Squalius lepidus is considered an intermittent spawner species. Growth parameters for both sexes were stated by the vonBertalanffy growth function as k = 0.162, L = 232mm, to = -0.427 years for females and k = 0.136, L =217mm, to =- 0.847 years for males. The weight-length relationship was described as W = 0.00005L 2.827 (r2= 0.860) for males and W = 0.00005 L2.855 (r2 = 0.859) for females. The slope of the regression line (b) fitted through the weight-length data suggested a negative allometric growth for both females and male (P<0.05)

Evaluation of filamentous fungal biomass cultivated on vinasse as an alternative nutrient source of fish feed : Protein, lipid, and mineral composition

The rapid growth of aquaculture and scarcity of conventional fish feed supplements has prompted the introduction of new sustainable supplementation sources. In this study, the potential of five strains of fungal biomass of Ascomycetes and Zygomycetes edible filamentous fungi, Aspergillus oryzae, Neurospora intermedia, Rizhopus oryzae, Monascus purpureus, and Fusarium venenatum, cultivated on vinasse, a by-product of the bioethanol industry, as alternative protein sources for fishmeal in the fish diet was evaluated. It was observed that 5% vinasse with an initial pH of 5-6.5 can support fungal biomass yields of 34.3 +/- 2.4-118.5 +/- 3.9 g DM/L for A. Oryzae, N. intermedia, and R. oryzae. High protein contents of about 44.7%, 57.6%, and 50.9% (w/w), and fat contents of 7.0%, 3.5%, and 5.5% (w/w) were obtained for A. oryzae, N. intermedia, and R. oryzae, respectively. The latter three fungi species contained noticeable amino acid contents, including promising profiles of amino acids that are highly compatible with those of fishmeal. These findings provide evidence that fungal biomasses, with their relatively high protein content, good amino acid profiles, and other essential nutrients, are a promising supplementation alternative that can be produced from low-value by-products and organic-rich waste streams like vinasse to meet the dietary protein requirements in fish feed