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The induction of tetraploidy by means of cold, heat and multiple heat shock treatments was investigated on male fish from a growth-enhanced transgenic tilapia C118 line, crossed with wild type females. After the development a new multiple heat shock protocol (two heat treatments at 41^oC in 60 and 80 min. after fertilization for 5 min. per each), chromosome and X-gal in situ staining assays demonstrated the successful production of yolk sac tetraploid transgenic tilapia in two out of 15 embryos examined in this trial via direct correlation between higher level of b-galactosidase expression and karyotyping in the samples verifying complete tetraploidy in this line. In the grown fish, there was evidence to suggest mosaicism or perhaps tetraploidy in at least two grown fish using the measurement of erythrocytes and karyotyping of the G1 offspring (p<0.05). There was, however, no evidence to indicate successful production of triploid G1 individuals following crossing of induced fish with wild type.

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 Nanotechnology presents countless opportunities to develop new and improved consumer products for the benefit of the society . A most prominent nanoproduct is nanosilver. Nanosilver particles are generally smaller than 100 nm and contain 20–15,000 silver atoms. Despite the wide application of nanomaterials, there is a serious lack of information concerning their impact on human health. In the previous study we reported the cytotoxic of nanosilver on osteoblast G292 cancer cell line and the amount of IC₅₀ determined as 3.42 µg/ml (Moaddab et al., Iran. Nano Lett., Vol. 1, No. 1, January 2011, pp. 11-16). The purpose of the present study is to assess the biological assay of nanosilver on two normal cell lines of fibroblast (HF2), and mesenchymal stem cells . The effect of nanosilver on these cells is evaluated by light microscopy, and by cell proliferation and standard cytotoxicity assays. The results demonstrate a concentration-dependent toxicity for the cells tested, and IC₅₀ was determined as 6.33, and 6.68 µg/ml in mesenchymal stem cell, and fibroblast HF2, respectively. There is no significant difference between the 24 h and 48 h of cells exposure to nanosilver. The results show that Nano-Ag possesses low toxicity to normal cells and can display potential application in cancer chemoprevention and chemotherapy.

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Euglenophyte bloom is a common problem in most of the aquaculture ponds in Bangladesh. In the present study we conducted an experiment to control euglenophyte bloom for achieving better fish production using duckweed (Lemna minor) and lime. The experiment was carried out using four treatments, i.e., ponds were supplied with duckweed (T1), lime treatment (T2), both duckweed and lime (T3) and without supply of duckweed and lime (T4). Rohu, catla, mrigal, silver carp and silver barb were stocked and their gut contents were analyzed monthly. The ranges of water quality parameters were analyzed within the productive limit during the experimental period. The mean abundance of euglenophyte was significantly highest in T4 (17.62 ± 1.97 x 10⁴ cells/L), followed by T2 (2.96 ± 0.20 x 10⁴ cells/L), T1 (1.94 ± 0.35 x 10⁴ cells/L) and T3 (1.53 ± 0.42 x 10⁴ cells/L). Gut content analysis revealed that considerable amounts of euglenophyte were consumed by silver carp and silver barb, but not preferred by rohu, catla and mrigal. The gross yields of fish were 2133.37, 1967.76, 2816.52 and 1725.62 kg/ha/5 months in T1, T2, T3 and T4 respectively. The highest fish production in T3 and lowest fish production in T4 indicated the use of duckweed and lime is economically sustainable for controlling euglenophytes bloom, maintaining water quality and getting higher fish production.

 

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Euglenophyte bloom is a common problem in most of the aquaculture ponds in Bangladesh. In the present study we conducted an experiment to control euglenophyte bloom for getting better fish production using duckweed (Lemna minor) and lime. The experiment was carried out using four treatments, i.e., ponds were supplied with duckweed (T1), lime treatment (T2), both duckweed and lime (T3) and without supply of duckweed and lime (T4). Rohu, catla, mrigal, silver carp and silver barb were stocked and their gut contents were analyzed monthly. The ranges of water quality parameters were analyzed within the productive limit during the experimental period. The mean abundance of euglenophyte was significantly highest in T4 (17.62 ± 1.97 × 10⁴ cells/L), followed by T2 (2.96 ± 0.20 × 10⁴ cells/L), T1 (1.94 ± 0.35 × 10⁴ cells/L) and T3 (1.53 ± 0.42 × 10⁴ cells/L). Gut content analysis revealed that considerable amount of euglenophyte were consumed by silver carp and silver barb, but not preferred by rohu, catla and mrigal. The gross yields of fish were 2133.37, 1967.76, 2816.52 and 1725.62 kg/ha/5 months in T1, T2, T3 and T4, respectively. The highest fish production in T3 and lowest fish production in T4 indicated the use of duckweed and lime is economically sustainable for controlling euglenophytes bloom, maintaining water quality and getting higher fish production.

 

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This study reports on the molecular identification of fish species from processed products which had a priori been classified as belonging to 5 important species in Iran for human consumption. DNA barcoding using direct sequencing of an approximately 650bp of mitochondrial Cytochrome oxidase subunit I (COI) gene revealed incorrect labeling of Narrow-barred Spanish mackerel samples. High occurrence of fraudulent fishery products, if left unchecked, can pose a negative impact on the economy. This investigation adds further concern on the trading of processed fish products in Iran from both health and conservation points of view.

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An investigation of the population parameters of Indian mackerel, Rastrelliger kanagurta (Cuvier, 1816) in the Marudu Bay, Sabah, Malaysia was carried out from January to September 2013. The relationship between total length and body weight was estimated as W=0.006TL3.215 or Log W=3.215LogTL – 2.22 (R2=0.946). Monthly length frequency data of R. kanagurta were analyzed by FiSAT software to evaluate the mortality rates and its exploitation level. Asymptotic length (Lµ) and growth co-efficient (K) were estimated at 27.83 cm and 1.50 yr-1, respectively. The growth performance index (φ') was calculated as 3.07. Total mortality (Z), natural mortality (M) and fishing mortality (F) was calculated at 4.44 yr-1, 2.46 yr-1 and 1.98 yr-1, respectively. Exploitation level (E) of R. kanagurta was found to be 0.45. The exploitation level was below the optimum level of exploitation (E=0.50). It is revealed that the stock of R. kanagurta was found to be still under exploited in Marudu Bay.

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Effects of salinity on fertilization, embryonic stage, and early larval development and growth performances of short-spined white sea urchin, Salmacis sphaeroides were conducted under a controlled laboratory condition. The experiment was carried out with seven salinity treatments (15, 20, 25, 30, 35, 40 and 45 PSU), each of which was triplicated. Significantly highest fertilization success was achieved at 30 PSU, followed by those at 25, 35, 20, 40 and 45 PSU, while the lowest value was obtained at 15 PSU, decreased with increasing and decreasing salinities (p<.05).The time required to reach these embryonic and larval stages was increased with the salinity deviations from 30 till the extent to 25 and 35 PSU. No significant differences (p>.05) were noted among these three salinity levels on prism larval length and width. However, significance differences (p>.05) were noted in morphometric characters of 2-arm and 4-arm pluteus larvae. The findings of the this study indicate that S. sphaeroides is stenohaline and do not survive and develop out of the range from 25 to 35 PSU.

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An experiment was undertaken to develop a suitable seed production technique for Sperata aor in captivity. Naturally produced fry of aor was reared at different densities in nine nursery ponds 0.012 ha in size with an average depth of 0.8 m each. Three stocking densities tested, each of which was triplicated. Fry of aor stocked at 100,000/ha was designated as treatment-1 (T1), 150,000/ha as treatment-2 (T2) and 200,000/ha as treatment-3 (T3). All stocked fry were from the same age group with mean length and weight of 1.78 ± 0.28 cm and 0.24 ± 0.05 g, respectively. Fry in all the treatments were fed with SABINCO nursery feed (32.06% crude protein) for the first 14 days and starter-I (31.53% crude protein) for days 15 to 56. Physico-chemical parameters and plankton population of pond water were within the optimal level being better in T1 than those in T2 and T3. Growth in terms of final weight and length, weight and length gain, specific growth rate, daily growth rate, and survival of fingerlings were significantly higher in T1 followed by T2 and T3. Food conversion rate was significantly lower in T1 than in T2 and T3. Significantly higher number of fingerlings was produced in T3 than those in T2 and T1. Despite this, consistently higher net benefits were achieved from T1 than from T2 and T3. This is the first time report that stocking of 100,000 fry/ha appears to be the most suitable density for rearing of aor fingerlings in nursery ponds.

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Diadema setosum (Leske, 1778), is one of the common echinoids widely distributed in the Indo-West Pacific Ocean, where it occurs from the Red Sea, Persian Gulf and the east coast of Africa to Japan, Australia and Malaysia. To investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of D. setosum in a controlled laboratory condition at the Institute of Bioscience, Universiti Putra Malaysia, during July–September, 2012. Matured gametes were obtained from the adult individuals and the eggs fertilized at limited sperm concentration (10-5 dilution). The obtained embryos were then reared at 24-25oC. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell and multi-cell (Morulla) stages were attained at 01.20, 02.14, 02.44, 03.09, 03.32 and 03.54 h after fertilization, respectively. Blastulae with a mean length of 111.47±1.88 µm (mean±SD) hatched 08.45 h after sperm entry. Gastrula formed 16.36 h post-fertilization and the archenteron extended constantly, while the ectodermal red-pigmented cells migrated synchronously to the apical plate. The pluteus larva started to feed unicellular algae (Chaetoceros calcitrans) in 2 d, grew continuously, and finally attained metamorphic competence within 35 d after fertilization. Induction of metamorphosis took approximately 1 h 30 min from attachment on the substratum to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event usually took place within 1 d post-settlement. The newly formed juvenile (473.16 ± 6.96 µm, n=30) with a complete adult structure then grew on coralline algae to 3-month old juvenile, which represents the “sea urchin seed” for stocking in grow-out culture. This study represents the first successful investigation on embryonic, larval and early juvenile development of D. setosum. The findings would greatly be helpful towards the development of breeding and seed production techniques for aquaculture of sea urchins.

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Different modified atmosphere conditions with various CO₂ concentrations on microbial load (psychrophile, mesophile aerobic and anaerobic bacteria) and physico-chemical properties of barramundi (Lates  calcarifer Bloch) fillets stored at 8°C were compared to determine the best packaging conditions. The gas conditions evaluated were 100% CO₂ (M₁), 75% CO₂/25% N₂ (M₂), 50% CO₂/50% N₂ (M₃), 25% CO₂/75% N₂ (M₄) and 100% N₂ (control). High CO₂ concentration (M₁ and M₂) of fish fillets delayed the psychrophilic bacteria growth compared to low CO₂ concentration (50% and 25% CO₂) as well as the mesophilic, anaerobic and histamine forming bacteria. We concluded that the atmosphere with 75:25% and 100:0 (CO₂:N₂) had the most appropriate gas composition to inhibit the microbial growth and prolong the shelf life of barramundi fillets (p<0.05). 

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Agunmukha River is an important water body having plentiful aquatic resources. The fisheries communities in the river are familiar with a diverse range of fishing gear and crafts to catch fish. Therefore, the objectives of the present study were to explore fishing gear and fishing crafts, catch composition of the respective gearand identification of fish biodiversity of Agunmukha River. A step wise validated questionnaire was used for data recording from February 2015 to August 2015. In total, 19 types of fishing gear were identified under 9 major categories. On the other hand, in view of fisheries biodiversity, 47 fish species were listed covering 28 families of which Cyprinidae was found as the most dominant family which contains 9 species under 7 genera followed by Bagridae having 5 species belonging to 3 genera and Engraulidae also containing 3 species under 3 different genera. The study described 7 vulnerable, 5 endangered and 2 critically endangered species out of 42 finfish species. Diversity indexes were calculated for the present finding of which Margalef’s index (d) was 5.13 for species available in the study area. Due to unawareness and indiscriminate fish caught with a small mesh size net, diversity of fish species in the river is under threat. Thus, public awareness and adequate knowledge on use of appropriate fishing gear with appropriate mesh size could contribute to sustainable fisheries diversity in the river and the improvement in livelihood of the fishermen in the adjacent area

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Sumithion is an organophosphorous pesticide widely used to control tiger bugs in fish larval rearing pond. The present study was aimed to investigate the effects of sumithion on plankton population abundance in aquaculture pond. The experiment was carried out with three treatments, i.e. ponds with no sumithion (T1), ponds with 1.0 ppm sumithion (T2) and those with 2.0 ppm sumithion (T3). The water quality parameters, such as temperature, pH, dissolved oxygen and total alkalinity were almost unchanged throughout the study period whereas transparency, NO₃-N and PO₄-P values declined with an increase in sumithion concentrations but differences were not significant (p<0.05). No distinct changes were observed in population densities of phytoplankton (x cells L^-1). On the other hand, the zooplankton population densities (x Ind L^-1) significantly (p<0.05) decreased with toxicity of sumithion after 30 days up to the end of experimental period in both T2 and T3 compared to the control group (T1). The ranges of pH, organic carbon (%), available phosphorus (ppm) and total nitrogen (%) of pond bottom-sediment did not differ irrespective of the treatments. This study demonstrated that sumithion has adverse effects on zooplankton which may influence the production in aquaculture pond. 

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Pomfrets are one of the most ample high priced fisheries of the Bay of Bengal, Bangladesh. The present study featuring the comparison of the life history parameters of three Pomfrets i.e. Silver (Pampus argenteus), Chinese (P. chinensis) and Black (Parastromateus niger) is based on the monthly length frequency data from the commercial landings from July 2015 through June 2016. The length (TL) of all three Pomfrets ranged from 8 to 55cm and weight (W) varied from 24 to 1302g. An allometric growth pattern was found in all cases when estimating LWR. The VBGF parameters for silver pomfret was L_∞= 54.6cm, K= 0.39yr^-1 while it was 54.6cm, 0.62yr^-1, 57.75cm, and 0.94yr^-1 for both Chinese and black pomfrets, respectively. Based on LCCC analysis the total mortality (Z), natural mortality (M) and fishing mortality (F) for silver and Chinese pomfrets were found to be the lowest compared with some previous studies related to the Indian Ocean, whereas black pomfret showed higher mortality rates to some extent. The exploitation ratio (E=F/Z) of silver and Chinese pomfrets were lower than the Gulland (1971) criterion of demarcation point of 0.5 and was higher for black pomfret which showed over-exploited stocks.  The YPR analysis also showed the heavily exploited state of black pomfret fishery, therefore, immediate management approach should be required to maintain sustainable stocks.
 

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Farming of the pacific  white leg shrimp (Penaeus vannamei), consists the greatest percent of aquaculture production of crustaceans all over the world. Vibriosis caused by Vibrio species such as Vibrio alginolyticus, is a serious limiting agent for aquaculture. Phage therapy is an eco-friendly alternative to antibiotics as a prophylactic measure for the growth of pathogenic bacteria. The aim of this study was isolation and characterization of Vibriophages present in Litopenaeus vannamei breeding and culture facilities and estuarine resources in south west of Iran, Choebdeh shrimp farming site of Abadan city, Khuzestan Province, based on morphological structure, biological conditions and their potential applications in lysis of Vibrio bacteria. The bacterial and phage samples were analyzed using different physicochemical parameters, 16S rRNA gene sequencing and TEM. The results showed the V. alginolyticus isolates and identified the Podoviridae family of phages. These bacterial isolates were resistant to ampicillin and penicillin. The efficacy of the Podoviridae phage against V. alginolyticus bacterium indicated that this phage has a short period of 30 minutes latent phase, possessed a desirable stability and growth in keeping for 1 hour at 30-55^oC, the salinity of 0.5-10  and pH of 5-8. Based on evaluation of phage therapy, mean absorbance values (OD₆₀₀), in control and treatment groups, at 12 and 24 hours after phage inoculation, were significantly different (p<0.05). According to the results, phage therapy with single-phage suspensions did not prevent bacterial regrowth after treatment. However, delay in development of resistance is a desirable success.

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Lack of information about ichthyofauna makes it difficult to predict human effects on the communities. In this study, the effects of the environmental and human factors were examined on altitudinal patterns of fish habitat selection, faunal changes, species richness and fish abundance from upstream to downstream in the southern part of the central Alborz Protected Area during 2016 and 2017. 366 fish individuals of five species in three families were identified and brown trout was the dominant species. The river was divided into three zones based on habitat structure, species composition and influence of physical and chemical variables. The results indicate that, in some situations, including small changes in habitat structure indices, physical and chemical variables along the altitudinal gradient are more effective in habitat preference, describing the composition, and abundance. Chemical variables can help to have a better understanding of the conventional patterns, shaped by the habitat structure and physical variables. Habitat suitability index model for brown trout in three zones is completely different over the two years and this species could overcome these conditions. However, upstream areas were more appropriate. Dam, with decreases of outlet water temperature, also creates homogeneous and simple habitats leading to changes in expected fish distribution patterns with decreasing altitude. These conditions may have increased habitat suitability index for the brown trout in downstream, while despite favorable ecological conditions in the middle zone, habitat suitability index and alternative habitats available in this zone are likely to decline due to density and interspecific competition. The natural pattern of fish distribution and habitat selection varies along the altitudinal gradient due to various factors and human disturbances. Optimal management of protected areas can control the effects of some of these factors at least temporarily.

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Shrimp polyculture with carp species has a great potential in economic development of Bangladesh. At present, shrimp polyculture technology is being most extensively used by shrimp farmers in the coastal regions of the country; however, the mechanism of scientific culture system is not well understood. Therefore, to evaluate the economic feasibility of shrimp (Penaeus monodon) polyculture with carp over mix culture of shrimp with prawn (Macrobrachium rosenbergii) and monoculture of shrimp, a study was conducted for a period of six months from July to December 2016 in selected ghers (modified low-lying rice fields with raised dykes, used for seasonal production of shrimp) at Kaliganj Upazila of Satkhira District, Bangladesh. Water quality was within the suitable range for shrimp culture. During the study period, environmental sustainability in terms of soil quality was achieved in polyculture of shrimp with carps and tilapia (Oreochromis niloticus). Growth performance and total yield of shrimp (2087.87±34.47 kg/ha) and prawn (1789.47±27.45 kg/ha) were also significantly (P<0.05) improved in polyculture of shrimp with carps and tilapia compared to shrimp monoculture and mix culture of prawn and shrimp, respectively. The economic sustainability was also found to achieve in polyculture of shrimp with carps and tilapia (Oreochromis niloticus) in terms of the Benefit-cost ratio (BCR), which was significantly (P<0.05) higher (2.49±0.03) compared to other culture systems (1.96±0.06 in shrimp monoculture and 1.26±0.03 in shrimp and prawn mix culture).

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Present study emphasizing the population dynamics parameters of Gray eel catfish (Plotosus canius) that was scrutinized based on monthly length frequency data collected from mangrove estuary, Bangladesh from January 2017 to December 2018. A total amount of 1298 specimens was collected to estimate the total length (TL) and weight (W) of P. canius ranged from 13.3cm to 87.4cm and 28g to 5200g respectively. The length-weight relationship was W=0.006 L^2.95 with R²=0.972 for both sexes. The von Bertalanffy growth function parameters were L∞=93.25cm and K=0.28yr^-1, hypothetical age at zero length of t₀=0.059 year and goodness of the fit of R_n=0.494. The growth performances indices for L_∞ and W_∞ were computed as Ø'=3.386 and Ø=1.84 respectively. The natural mortality was 0.51yr^-1 at average annual water surface temperature as 22^°C. The total instantaneous mortality was 1.24yr^-1 at CI_95% of 1.05–1.42 (r²=0.986). While fishing mortality was 0.73yr^-1 and the current exploitation ratio as 0.59. The recruitment was continued throughout the year with one major peak during June-July was 17.20-17.96%. The Beverton-Holt yield per recruit model was analyzed by FiSAT-II, when t_c was at 1.443 yr, the F_max was estimated as 0.6yr^-1 and F_0.1 was 0.33yr^-1. At the age of 0.6 year, F_current was 0.74yr^-1 that is beyond the F_0.1 that specified the current stock of P. canius of Bangladesh was over-exploited.

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Our study describes the stock status of Planiliza subviridis (Valenciennies, 1836) by emphasizing on growth pattern, growth parameters (asymptotic length, L_∞; asymptotic weight, W_∞; growth co-efficient, K; age at zero length, t₀), sexual maturity size (L_m), age at sexual maturity (t_m), growth performance index (Ø'), life-span (t_max), relative weight (W_R), form factor (a_3.0), mortality rates ( Z, M and F), exploitation rate (E), maximum sustainable yield (MSY), and relative biomass of P. subviridis from the coastal Shibsa River, Southern Bangladesh. A sum of 317 individuals of P. subviridis ranging from 6.50-19.70 cm total length (TL) was sampled during July 2017 to December 2019. The overall b value indicated isometric growth (b = 3.0) pattern. The estimated L_∞, W_∞, K, and t₀ were 20.79 cm, 93.20 g, 1.02 per year, and 0.015 year, respectively. The L_m was estimated as 11.65 cm in TL and t_m was 0.82 year. The t_max was 2.93 year and Ø' was 2.64. Fulton’s condition factor was found most suitable for this species. Further, the average relative weight (W_R) indicated that the habitat was in a stable situation. In addition, the Z, M, and F were obtained as 2.23, 1.57, and 0.66 year^-1, respectively. Length at maximum yield per recruit (L_opt) was estimated as 13.74 cm. Further, the E (0.30) and MSY, maximum sustainable Yield (0.29) indicated balance harvesting occurred in the coastal Shibsa River. Additionally, the relative numbers of survival, individual growth in weight, and cohort biomass was 24%, 40.0 g, and 100% (9.0 kg) when P. subviridis reached 1.2 years. Consequently, the results of our study will be supportive to implement a proper management strategy in the coastal Shibsa River and adjoining ecosystems of Bangladesh.