Growth performance of 17 alpha-methyl testosterone treated monosex and hormone untreated mixed sex tilapia was done for a period of 180 days in cages adjacent to Lwanda Disi beach, Lake Victoria, Kenya. Mixed sex Nile tilapia is known for frequent spawning in culture systems, resulting to fish with varied sizes and stunted growth. To attain male monosex fingerlings, the newly hatched fry were sex reversed by feeding them a diet laced with 17-alpha-methyl testosterone hormone for 21 days. Thereafter, the fry were fed 40% crude protein (CP) diet until stocking into cages. Mixed sex fry of same cohort were fed 40% crude protein starter diet until the time of stocking. A total of 6 cages (2×2×2 m) were randomly stocked with 1000 male monosex and mixed sex fingerlings. The individual mean (± SD) weight at stocking was 9.5 ± 0.06 g and 8.8 ± 0.08 for monosex and mixed sex, respectively. The experimental fish were fed starter diet 40% CP at 10% of body weight for the first two months. From the third month till the end of the experiment, the fish were fed 30 CP diet at 3% of body weight. Measurement of fish total length, body weight and selected water quality parameters was done once a month. There was a significantly higher (P < 0.05) mean body weight gain (BWG), specific growth rate (SGR) and condition factor (CF) for male monosex fish. Conversely, Feed conversion ratio (FCR) was significantly higher (P < 0.05) in mixed sex Nile tilapia. Survival rates (%) and water quality parameters did not differ between the groups. Though the mixed sex Nile tilapia did not reproduce in cages they performed poorly compared to male monosex.

Heavy metal contaminations may have devastating effects on the ecological balance of the environment and diversity of aquatic organisms. Furthermore, they cause great threat to the Indian aquatic ecosystem. In this study, we analyzed the effect of arsenic (As) and lead (Pb) on the blood glucose level and their possible involvement in the mitogen-activated protein kinase (MAPK) pathway in liver and muscle tissues of Heteropneustes fossilis. The catfish, H. fossilis, were exposed to an acute (35.09 ppm As2O3 and 66.20 ppm PbCl2 for ~96 h) and chronic (LC50/20th ppm of both As2O3 and PbCl2 for ~30 d) concentration of As and Pb. Thereafter, the blood glucose level and the extracellular signal-regulated protein kinase (ERK) expression level in liver and muscle tissues of the fish were analyzed. It was found that As and Pb caused hyperglycemia in H. fossilis. Both on acute and chronic treatment with As and Pb, no significant change in p-ERK1/2 expression level was found in the muscle tissue of H. fossilis, whereas, in the liver tissue, the p-ERK1/2 expression level showed a significant increase in both acute (96 h) and chronic treatment (10 d and 30 d) of As and Pb. Therefore, it can be concluded that As and Pb could be highly toxic to the aquatic fauna, which could be a potential threat to human health as well.

Sperm activation and short-term storage have important implications in breeding programs. Although silver carp, Hypophthalmicthys molitrix, is an important aquaculture species in South Asia, information on sperm biology and storage is limited. The study aims to test the efficacy of NaCl solutions for activation and short-term storage of silver carp sperm. We found that the motility of silver carp sperm lasted for 45 sec after activation in distilled water. Sperm motility was higher within the first 10 sec of sperm activation, but sperm movement decreased with increasing activation time. When sperm was suspended a graded dilution of NaCl solutions (17 mM to 188 mM), sperm was immobilized at 154mM NaCl (287 mOsmol kg–1). The efficacy of sperm immobilizing solutions was validated during short-term storage at 4°C. A total of 7.1 ± 3.1% sperm was motile in 154 mM NaCl after 5 days of storage. Sperm motility lasted up to 2 days when sperm diluted in 103, 120, 171 and 188 mM NaCl solutions. The osmotic balance between seminal plasma and NaCl solution prepared at 154 mM prevented sperm activation and provided a suitable media for short-term storage. A 154 mM NaCl solution can be used for sperm collection and short-term storage of silver carp sperm.

Changes in the expression of liver insulin-like growth factor IGF-I mRNA in two growing cold-water fish species Oncorhynchusmykiss(one from locally produced and one from imported broodstock) and in two warm-water species, Hypophthalmichthysnobilis and Hypophthalmichthysmolitrix were analyzed. Gene expression analysis in liver tissues by using real-time PCR revealed a significant difference in expression level of IGF-I between native and non-native rainbow trout (P bighead carp> silver carp> native rainbow trout. Local strains of rainbow trout, bighead carp and silver carp exhibited stable IGF-I mRNA levels, at different stages of growth. The imported broodstock of rainbow trout exhibited increased IGF-I levels during the entire period studied, with a peak in the IGF-I mRNA levels of fingerlings. The results indicate intra- and inter-specific variability of IGF-I expression in farmed fish.

In the wild, overfishing, habitat loss, industrial and agriculture activity has led to the degradation of freshwater habitats and, therefore, dramatically declines the Mississippi paddlefish (Polyodon spathula) stocks (Stone 2007). Paddlefish gain a growing commercial interest in the USSR/Russian Federation due to its ability to produce high-quality caviar. Also, it can be reared in polyculture ponds and a wide range of temperate reservoirs. Therefore, aquaculture of these valuable fish is necessary to meet consumer demand in Eastern European markets with flesh and caviar. Published information about the culture of paddlefish in the USSR/Russian Federation is scarce and not permanently available. Regarding our study, data were collected from English reports and translated Russian official statistics and studies. Also, FAO fisheries data from 1880 up to 2010 for paddlefish were included. Moreover, caviar production data and prices were surveyed from companies. The collected data could briefly represent the historical and current status of paddlefish aquaculture and provide insight into the expected future production in the Russian Federation. Besides, it investigates the drawbacks of paddlefish aquaculture development and the potential challenges in Russian territories. Also, it discusses potential impacts related to the preservation of the breeding stocks, population naturalization and invasiveness of the species in the southern parts of Russia (i.e., in the Volga‐Caspian basin): Saratov, Rostov, Astrakhan Oblast and Krasnodar regions. Furthermore, this review aimed to gather the available data and the latest final findings that may address the welfare of paddlefish data to fill the knowledge gap towards improving the management of this species. In addition, future development prospects can be supported by government oversight through accurate accounting and financing for private farm activity.

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The objective of this study was to assess the biologic impact of four diets based on three species of microalgae on the Mediterranean mussels Mytilus galloprovincialis. For this purpose, flesh weight, linear growth, survival rate and the biochemical composition of mussel flesh have been evaluated. Mussels fed with a mixture of the three species; Nannochloropsis sp., Dunaliella sp., and Phaeodactylum sp., exhibited the highest lipid level (7.66%). This suggests that mixing several species in the same diet favors lipid production. Protein level was significantly higher in mussels fed with Dunaliella sp. (28.92%) compared to Phaeodactylum sp (24.52%), Nannochloropsis sp. (22.94%) and a combination of the three species (26.07%). Wet weight gain was significantly higher in mussels fed with Dunaliella sp. (7.76 g) compared to mussels fed with the mixture of the three species (6.87 g). However, mussel shell length was not different among the four groups, and ranged between 41.7 mm and 42.3 mm. In conclusion, the data from this study suggest that a diet based on Dunaliella sp. can efficiently cover the protein requirements of the Mediterranean mussel, Mytilus galloprovincialis during the growth cycle.

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This feeding trial aimed to evaluate the effect of a natural dietary supplement with proposed immunostimulant and related biological activities on growth performance and muscle growth markers in rainbow trout, Oncorhynchus mykiss. Fish grown in cages were fed either a commercial diet (control) or a diet supplemented with dihydroquercetin and arabinogalactan at a dosage of 25 and 50 mg kg⁻¹ of feed, respectively, during the summer-autumn season. Unplanned infectious disease did not interfere with the scheme of the experiment since both groups were infected and then treated with antibiotics. Significant differences in growth parameters between the control and experimental groups were shown only in a few cases; however, their body weight and length, Fulton’s condition factor, and relative growth rate tended to be higher in the fish fed the diet with supplements. Bacterial infection influenced muscle growth mechanisms and protein turnover through partial suppression of myosin heavy chain (MyHC) expression and proteasome activity. In fish fed the experimental diet, MyHC expression was higher throughout the experiment and was more readily restored during the post-infection period. In the experimental group, the system of protein quality control involving proteasome activity was less perturbed by infection. Moreover, the suppression of the protein-degrading capacity of calpains found in the muscles of fish fed the experimental diet probably demonstrates a mechanism of growth acceleration during the post-infection period. Therefore, in infected rainbow trout, the experimental diet diminished the effects of the disease and substantially promoted post-infection repair, improving survival and infection tolerance and affecting growth mechanisms in fish.

Heavy metals show a wide range of effect on fishes, out of which arsenic (As) and lead (Pb) are among the leading heavy metal toxicants. These heavy metals are known to alter different biochemical parameters, including glycogen level, in different tissues of fishes. Glycogen level in fish serves as the main source of energy; hence, in this study, the acute toxicity test of As and Pb and their effect on the glycogen content and the enzymes involved therein (glycogen phosphorylase, glycogen synthase, hexokinase, phosphofructokinase and pyruvate kinase) were studied in the liver and muscle tissues of Heteropneustes fossilis. The 96 h LC50 values of As2O3 and PbCl2 on H. fossilis were found to be 35.09 ppm and 66.20 ppm, respectively. On acute exposure to 96 h LC50 values of As2O3 and PbCl2, the glycogen concentration showed a gradual decrease in both liver and muscle tissues of H. fossilis. However, on chronic exposure (LC50/20th ppm), the glycogen content in liver and muscle of H. fossilis was depleted till 20 days; whereas after 30 days, the glycogen level was recovered in both the tissues. The activities of glycogen metabolic enzymes (glycogen phosphorylase and glycogen synthase) and few selected glycolytic enzymes (hexokinase, phosphofructokinase and pyruvate kinase) were also altered in H. fossilis when exposed to acute and chronic concentration of As2O3 and PbCl2. Our present results showed that As and Pb induced toxicity stress on the catfish, H. fossilis, which might have caused to alter the carbohydrate metabolism in the fish.