International Journal of Aquatic Biology
Volume:3 Issue: 2, Apr 2015

The present study was conducted to evaluate the effect of dietary inclusion of silver nanoparticle on general performance and digestive proteases in zebra fish. Four experimental diets were designed with a concentration of 5, 20 and 40 parts per billion (ppb) nanoparticles in the diet (named S5, S20, and S40, respectively) and control group without any nanoparticles (S0). There was no significant difference was observed in FI and FCR between the dietary treatments. At the end of the experiment, S20 exhibited highest WG and SGR followed by S40 compared with other treatments while, there was no significant difference observed between S0 and S5. Similar trends were also observed in total protease enzyme activity. To evaluate the protease enzyme patterns on gut extract, substrate SDS-PAGE was performed and the inhibition of zymogram was studied. The results showed that there was no difference in banding patterns between S0 and S5 with EDTA treated samples whereas two extra bands of molecular weight (MW) 67 and 37 appeared in S20 and S40, were inhibited by EDTA indicating the presence of metalloprotease in those dietary regimes. There were no differences in the banding patterns of PMSF treated samples suggesting that the total serine protease remains unaffected by the dietary regimes. To conclude, we found 20 ppb inclusion of silver nanoparticle in fish diet improves general performance and induces metalloprotease activity in fish. Further detailed study is required before establishing dietary inclusion of silver nanoparticle for industrial purposes.

Streptococcus iniae has emerged as an important fish pathogen over the last decade in farmed rainbow trout in Iran. The main objective of this study was to evaluate the pathogenicity of S. iniae in Poecilia reticulata. Atotal of 60 apparently healthy P. reticulata were obtained from ornamental fish pet store and injected intraperitoneally with 1.5×106 cfu of bacteria. For 14 days after challenge, the rate of mortality and clinical signs were recorded. The first clinical signs was observed in challenged fish 48 hrs after injection of S. iniae and first mortality was observed 72 hrs after injection. No significant differences in mortality and clinical signs between both sexes were observed. Streptococcus iniae was collected from internal organs of fishes challenged, and was confirmed using the conventional biochemical tests and PCR. It is concluded that, P. reticulata is susceptible to streptococcosis and can play an important role in transmission of the disease to other ornamental fish species and also cultured fish.

In this study, the effects of dietary egg lecithin on digestive enzymes and body biochemical composition of juveniles Mesopotamichthys sharpeyi was evaluated. Four experimental diets including control diet (with 0% egg lecithin) and three diets containing 2%, 4% and 6% egg lecithin were used. At the end of the experiment, digestive enzymes activity (lipase, amylase and alkaline phosphatase) and body biochemical compositions were assessed. The results showed no significant differences between experimental treatments in moisture and ash content. Maximum content of the crude protein and crude lipid were recorded in 4% lecithin treatment and it had significant differences with control group. The digestive enzymes activity (lipase, amylase and alkaline phosphatase) showed significant differences between control and experimental groups. An increasing trend was observed in the digestive enzymes activity among treatments. Based on the results, it was concluded that 4% to 6% dietary egg lecithin in the diet, can promote growth and survival rate of juvenile binni.

Plankton and semi-plankton samples collected from twelve floodplain lakes (beels) of Majuli River Island of the Brahmaputra river basin, Upper Assam reveal rich Cladocera assemblage of 48 species belonging to 32 genera and 7 families. This report assumes biodiversity value as ~65.0% and ~37.0% of the species, and ~78.0% and ~72.0 of genera of the taxon known from Assam state of northeast India (NEI) and India, respectively. Picripleuroxus quasidenticulatus (Smirnov) is a new record from the Indian sub-region. Biogeographically important elements include one Australasian, three Indo-Chinese and two Oriental species. Total cladoceran richness in individual beels ranged between 16-38 (26 ± 6) species while monthly and seasonal richness in six beels each varied between 8 ± 3-13 ± 3 species and 11 ± 4-17 ± 3 species, respectively and showed lack of any pattern of temporal variations. The community similarities (40.1-86.5% vide Sørensen’s index) and the hierarchical cluster analysis affirm heterogeneity in Cladocera composition in different beels. Individual abiotic factors indicated insignificant influence on richness except for significant positive correlation with alkalinity only in Khorkhoria beel.

Sesame oil cake (SSC) was bio-processed through solid state fermentation (SSF) under optimized conditions by a phytase-producing fish gut bacterium, Bacillus subtilis subsp. subtilis (JX292128). SSF significantly reduced anti-nutritional factors (e.g., phytic acid, tannins and trypsin inhibitor) and crude fibre, while enhanced free amino acids, fatty acids and different minerals. Phytase production (39.72 ± 1.06 U/g) during SSF was also recorded. Along with a fish meal based reference diet (RD), 8 isonitrogenous (36% crude protein) and isocaloric (4.60 kcal g-1) experimental diets incorporating raw (R1-R4) and SSF processed (F1-F4) SSC(20%, 30%, 40% and 50%, w/w) were fed to rohu, Labeo rohita fingerlings (mean weight 3.28 ± 0.15 g) in triplicate treatments for 70 days. In general, growth and feed utilization efficiencies in fish fed diets containing SSF-processed SSC were superior to the groups fed diets containing raw SSC. The diet F3 (40% fermented SSC) showed significantly (P<0.05) better result in terms of weight gain, feed conversion ratio, protein efficiency ratio, apparent net protein utilization, activities of digestive enzymes, carcass composition and apparent digestibility of protein, lipid and phosphorus. Faecal phosphorus discharge reduced significantly (P<0.05) in fish fed fermented diets. The results indicated that incorporation of SSF-processed SSC might be practiced as a function to replace fish meal in the diets of L. rohita fingerlings.

In this study gill-net selectivity for Alburnus chalcoides inhabiting the Almus Dam Lake was estimated. Experimental gill-net fishing was conducted using gill-net with 15 mm and 20 mm mesh-size, during October 2002 and September 2003. A total of 254 and 198 specimens of A. chalcoides were caught by gill-net with 15 mm and 198 with the 20 mm mesh-size, respectively. The total length of the fish ranged from 10.5 cm to 21.5 cm for 15 mm mesh-size and 13.6 cm to 25.6 cm for 20 mm mesh-size. Mean total lengths were calculated as 14.34 ± 1.52 cm and 17.85 ± 1.97 cm for 15 mm and 20 mm mesh-size, respectively. Selectivity analysis indicated an optimum length (100% probability of retention) of 14.77 cm for the 15 mm mesh size and 19.69 cm for the 20 mm mesh size gill-nets. Selectivity Factor was calculated as 0.9846. The vast majority (81%) of fish caught by 15 mm mesh size and 20 mm mesh size were mature. Therefore, both the 15 mm and 20 mm mesh size were suitable for the sustainable fisheries of A. chalcoides in the Almus Dam Lake.

The effects of grape pomace extract (0, 2 and 4%) on quality and shelf life of silver carp (Hypophthalmicthys molitrix) fillets during chill storage (4°C) were investigated. The control and the treated fillets were analyzed periodically for microbiological (TVC and PTC), chemical (TVB-N), and sensory characteristics. The results showed that grape pomace-treated samples have lower TVB-N (24.2 and 21.2 mg N/100 g, respectively), TVC (7.33 and 7.09 log cfu/g, respectively) and PTC (7.26 and 7.03 log cfu/g, respectively) at the end of the storage period. The results revealed that the addition of grape pomace extract has a positive effect on the sensory quality of silver carp fillets by retaining proper quality characteristics for a longer time and extends their shelf life during chill storage.

Length-weight relationship is the most commonly used analysis which has been used for several purposes in fisheries field among which estimation of weight from length is the most popular one. The present study has been performed to analyze the length-weight relationship of Mystus tengara, a freshwater catfish of Indian subcontinent. Total Length and Body Weight of the studied specimens have been observed to vary from 7.2-11.3 cm (male), 7.3-11.7 cm (female) and 3.43-13.63 g (male), 2.83-14.88 g (female). The calculated regression coefficient (b) values are 2.941, 3.119 and 3.071 for male, female and combined sex, respectively; thus depicting negative allometric growth for male; while positive allometric growth for female and combined sex of this fish species. The correlation coefficient values (0.94, 0.95 and 0.95 for male, female and combined sex, respectively) are suggesting a significant relationship between length and weight of the studied fish. The present study provides the first baseline information on the length weight relationship of M. tengara which will be beneficial for future management of this fish species.

The present study provides the data on the population parameters of an endemic qanat spirlin, Alburnoides qanati from the endorheic Kor River basin of Iran to assess the stock status of this cyprinid fish species, which is highly important from management and conservation points of views. Fish specimens (387) were collected from Moshkan Stream, Kor River basin, Iran in 2011-2012. Asymptotic length (L∞) and growth coefficient (K) were estimated at 123.9 mm and 0.31/year for females and 93 mm and 0.49/year for males, respectively. Growth performance index (Ø'') was calculated as 8.47 and 8.35 for female and male specimens, respectively. Total mortality (Z) of females (1.56/year) was higher than males (1.14/year) whereas natural mortality (M) of female specimens (0.44/year) was lower than male specimens (0.65/year). Data on growth and mortality parameters and also length-weight relationship of A. qanati revealed significant differences with corresponding data from other Alburnoides species from Iran and other countries, which could be attributed to habitat’s differences and specific species characteristics.