Bioaccumulation and depuration of chromium in the selected organs and whole body tissues of freshwater fish Cirrhinus mrigala individually and in binary solutions with nickel

Contamination of aquatic ecosystems with heavy metals has been receiving increased worldwide attention due to their harmful effects on human health and other organisms in the environment. Most of the studies dealing with toxic effects of metals deal with single metal species, while the aquatic organisms are typically exposed to mixtures of metals. Hence, in order to provide data supporting the usefulness of freshwater fish as indicators of heavy metal pollution, it has been proposed in the present study to investigate the bioaccumulation and depuration of chromium in the selected organs of freshwater fingerlings Cirrhinus mrigala, individually and in binary solutions with nickel. The results show that the kidney is a target organ for chromium accumulation, which implies that it is also the ＂critical＂ organ for toxic symptoms. The results further show that accumulation of nickel in all the tissues of C. mrigala is higher than that of chromium. In addition, the metal accumulations of the binary mixtures of chromium and nickel are substantially higher than those of the individual metals, indicating synergistic interactions between the two metals. Theoretically the simplest explanation for an additive joint action of toxicants in a mixture is that they act in a qualitatively similar way. The observed data suggest that C. mrigala could be suitable monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats.

Length-weight relationships for six freshwater fish species in Iran

The aim of this study is to report the length-weight relationship parameters （a and b） for some economically important fish species from Iranian freshwaters. The length-weight relationships （LWR） are calculated for six freshwater fish species collected during 2006 and 2007 in Iran. The values of the exponent b in the LWR （W=aL^b） vary between 2.985 and 3.543. The LWR with high correlation coefficient （r^2） is significant for all the species. These parameters axe of great importance to evaluate the relative condition of populations, biology, species management and their fisheries and stock assessment. The application of the length-weight relationships presented here should be limited to the observed length ranges.

Development of Intermediate Foodstuff Derived from Freshwater Fish in China

According to the three-dimensional contour maps showing the gel-forming properties of surimi derived from freshwater fish, 8 species of surimi were classified into two types. The-valley type surimi （silver carp, big-head carp, Chinese snake head and blunt snout bream） shows easy setting, low resistance to gel collapse, high enhancement ability with two-step heating, and narrow optimum heating temperature and time area, which are of the same characteristics as the walleye pollack surimi. In contrast, the Plateau type surimi （tilapia, grass carp, mud carp and common carp） exhibits difficult setting, high resistance to gel collapse, no enhancement ability with two-step heating, and wide optimum heating temperature and time area. There are seasonal changes of gelling properties of silver carp surimi, and the setting ability of surimi gel is higher in winter and lower in summer. The marine fish meat gels and the freshwater fish meat gels have the same acceptability for inland Chinese according to the sensory evaluation results. A slight increase in sensory scorings of kamaboko gels occurred when the extract from walleye pollack muscle was added, especially in the odor scoring of silver carp kamaboko gels.

BIODIVERSITY AND CONSERVATION OF FRESHWATER FISH IN HONG KONG, CHINA

We surveyed the distribution, composition and diversity of freshwater fish in Hong Kong, China from 2002 to 2004. Sites surveyed were mainly streams, marshes and estuaries. There are ponds for aquaculture and reservoirs in Hong Kong but no large natural water bodies. From the 220 sites surveyed, 114 species of 37 families were found. Gobiidae (with 24 species) and Cyprinidae (21 species) were the dominant families. This survey has increased the number of freshwater fish species recorded in Hong Kong to 167. Among these, 71 (42.5%) are primary freshwater fish, 44 are brackish and 46 are vagrants. The remaining 6 species are diadromous. In Hong Kong, freshwater fish are conserved by a combination of measures. About 38% of Hong Kong’s land area is designated as country parks and/or special areas, and is managed for nature conservation and educational purposes. In addition, another 5% of land area is zoned for conservation in the statutory land use zoning system to protect them from development and incompatible land uses. Major development projects have to go through the statutory environmental impact assessment process to ensure that they will not have adverse impact as far as practicable. There are conservation action plans for important species. For example, captive-bred individuals of the endemic Hong Kong Paradise Fish Macropodus hongkongensis have been released to suitable and secure sites inside country parks and their populations are regularly monitored. Other measures such as wetland creation, restoration and enhancement programmes are also implemented for freshwater fish conservation.

Microbial Load (Bacteria, Coliform and Mould Count/Flora) of Some Common Hot Smoked Freshwater Fish Species Using Different Packaging Materials

Three different packaging materials of (37 cm × 25 cm) size (Sealed Transparent Polythene Bag (STPB) Sealed Paper Bag (SPB) (Brown envelope), Open Mouth Polythene Bag (OMPB) (Black incolour)) were used for Oreochromisniloticus (O), Clariasgariepinus (C) and Mormyrusrume (M). Twenty fish samples per species (averaging 250 gm) were hot smoked dried whole for 36 hours at an average temperature of 100?C. Packaged hot at the rate of 6 fishes per package for each species (three packs for each packaging treatment i.e. 18 pieces were packed while the remaining 2 pieces were used for initial bacteria load and microbial load). Microbial load (Total Viable Count (TVC), Total Coliform Count (TCC) and Total Fungi Count (TFC)) for the fresh fish was initial hot smoked and finally at the end of 12 weeks was monitored. The TVC (bacterial load) of O. niloticus dropped from (10.6 - 8.4) × 104 (fresh state-hot smoked) and M. rume (9.8 - 7.0) × 104, while C. gariepinus slightly increased from (12.4 - 12.6) × 104. After hot smoking, highest TVC of 8.6 × 104 (OMPBC), 8.3 × 104 (SPBC) and 8.2 × 104 (STPBC) were recorded in C. gariepinus among the 9 packag- ing at 12 weeks. However highest tendency for heavy TVC is in all OMPB with highest bacteria load in the OMPBC (8.6 × 104), 7.6 × 104 (OMPBO) and 6.6 × 104 (OMPBM). After 12 weeks highest ranged TFC of (0.6 - 0.7) × 104 was recorded in M. rume as against 0.2 × 104 recorded in the initial smoked for all. TCC was highest in C. gariepinus (4.0 - 4.3) × 104. Packaging did not limit the existence of micro-organisms. Six bacteria species (Micrococcus (acidiophilus, luteus), Bacillus (subtilis, cereus, aureus), Staphylococcus aureus, Streptococcus lactis, Proteus (vulgaricus, morganii), Pseudomonas aureginosa) and three fungi species (Aspergillus (niger, tamari), Rhizopusnigricans, fusariumoxysporum) were represented in all the packages. On the average five bacteria and two fungi species were represented, excepting for OMPBM and OMPBO with six bacteria species.

Strategic Conception for Sustainable Development of Massive Freshwater Fish in China

[ Objective] To propose strategic conception for sustainable development of massive freshwater fish in China. [ Method] The current development status of massive freshwater fish industry in China was analyzed. On this basis, strategic conception for sustainable development of massive freshwater fish in China was proposed. [Remlt] In order to solve the present problems in the massive freshwater fish industry in China, basic strategies were proposed to develop the massive freshwater fish industry in China. The fishery resources should be capitalized to promote sustainable development of resources. Consumer demand of end-market should be used to drive stable development of the whole industry chain. Consumer demand should be guided to enhance the industrial market position. Processing and distribution channels should be constructed to promote sustainable development of seed and farming industries. Consumer demand at different levels should be used to promote multi-level multi-media health culture. Brand building and operating should be performed to enhance the competitive position of the industry in international and domestic markets. [ Condusion] The study has great theoretical and practical significance for promoting development of the massive freshwater fish industry in China.

Productive Performance of Giant Freshwater Prawn （Macrobrachium rosenbergi） Fed Diet Containing Silkworm Pupae （Bombyx mon~ Replacing for Fish Meal

The productive performance of giant freshwater prawn （Macrobrachium rosenbergii de Man） fed diet containing silkworm pupae （Bombyx mori） replacing for fish meal was conducted by focusing on digestibility, growth performance and feed utilization. Five diets of an isonitrogenous of 35 ：e 1% crude protein and isocaloric of digestible energy of 3,200 ±100 kcal/kg were formulated by using silkworm pupae, 0%, 8.6%, 17.2%, 25.8% and 34.7% by weight, replaced for fish meal. Giant freshwater prawn of 19 ± 2.0 g were stocked at 5 ind./m3 in concrete tank of 2.25 ton for three months. The protein digestibility by pepsin enzyme was evaluated in fish meal, silkworm pupae, soybean meal and shrimp meal. The digestibility was significantly difference （P 〈 0.05）. The protein digestibility of fishmeal and soybean meal was higher than silkworm pupae and shrimp meal. The productive performance of prawn in terms of growth rate and feed utilization were not significantly different （P 〉 0.05）. Therefore, silkworm pupae can be replaced for fishmeal in giant freshwater prawn （Macrobrachium rosenbergii de Man） without any adverse effects on productive performance.

Distribution and Relationships of Seven Trace Elements （Cr, Fe, Mn, Ni, Co, Cu and Zn） in Freshwater Fish from Five French Fishing Areas

The concentrations of seven essential trace elements in 149 freshwater fish from eight fish species （European eel, bream, common carp, European catfish, roach, perch, pike and pikeperch） from five different French fishing areas from contaminated and control sites were measured by inductively coupled plasma mass spectrometry after microwave digestion under pressure. Differences in the concentration of elements in the muscles of these species were examined and the mean levels were compared for each species with previous French and European studies. The condition factor and the differences between the control and contaminated sites and between predatory and non-predatory groups, with respect to the concentration of these elements, were also studied.

Maintaining Biodiversity in Freshwater Ecosystems on Oceanic Islands of the Tropical Pacific

Stream animals on tropical high islands have ecological counterparts among continental fauna but are confronted with highly dynamic and variable environmental conditions that can far exceed those occurring in mainland streams.In response to weather fronts passing through an island chain or to localized fluctuations in the formation of orographic rain,water levels in island streams can change from low flows of a few centimeters depth to sudden flash floods of several meters and back to clear shallow water within a few days.Studies of the five species of indigenous Hawaiian stream fishes have shown that the dispersal of larvae out to sea and their return several months later during their amphidromous life cycles constantly restock streams and provide a kind of ready reserve for recolonizing streams after unusually harsh disturbances,such as the recent Hurricane Iniki.Because of the predominance of amphidromy among the major species of stream fishes and macroinvertebrates on tropical Pacific high islan s,we hypothesize that maintaining biodiversity in these island streams when conditions are otherwise favorable and restoring animal life to formerly diverted streams may be no more complicated than assuring that the freshwater-marine threshold remains open and that natural fluctuations in flow are unhampered.

Zoonotic human liver flukes,a type 1 biocarcinogen,in freshwater fishes:genetic analysis and confirmation of molluscan vectors and reservoir hosts in Bangladesh

Background Opisthorchiid flukes,particularly Opisthorchis viverrini,Opisthorchis felineus,Clonorchis sinensis,and Metorchis spp.are the most common fish-borne zoonotic human liver flukes(hLFs).Liver fluke infections are more prevalent in resource-deprived and underprivileged areas.We herein estimated the prevalence of the metacercariae(MC)of major hLFs in common large freshwater fishes(lFWF)marketed for human consumption from some selected areas of Bangladesh along with detection of their molluscan vectors and reservoirs.Methods The current status of fish-borne zoonotic hLF infections in lFWF was investigated along with their molluscan vectors and mammalian reservoir hosts in Mymensingh and Kishoreganj in Bangladesh from July 2018-June 2022 using conventional and multiple molecular techniques,such as PCR,PCR-restriction fragment length polymorphism(RFLP),sequencing,and bioinformatic analyses.The infection rate of fishes was analyzed using the Z-test and the loads of MC were compared using the chi-squared(χ^(2))test.Results The MC of C.sinensis,Opisthorchis spp.,and Metorchis spp.were detected in 11 species of common and popular lFWF.In lFWF,the estimated prevalence was 18.7%and the mean load was 137.4±149.8 MC per 100 g of fish.The prevalence was the highest(P<0.05)in spotted snakehead fishes(Channa punctata,63.6%).The highest rate of infection(P<0.05)was observed with the MC of C.sinensis(11.8%).Metacercariae were almost equally(P>0.05)distributed between the head and body of fishes.The infection rate was slightly higher in cultured(19.6%)fishes.The MC of C.sinensis,O.felineus,O.viverrini,and Metorchis orientalis in fishes were confirmed using PCR,PCR-RFLP and bioinformatics.The cercariae of opisthorchiid(Pleurolophocercus cercariae)flukes were only recovered from Bithynia spp.(3.9%,42 out of 1089).The ova of hLFs from dogs(4.3%,5 out of 116)and cats(6.0%,6 out of 100),and adult flukes(M.orientalis)from ducks(41.1%113 out of 275)were detected.Conclusions The MC of hLFs are highly prevalent in fresh water fishes in Bangladesh.Reservoir hosts,such as street dogs,cats,and ducks carried the patent infection,and residents of Bangladesh are at risk.

Temporal Distribution of Fish Community Structure in Dongting Lake Estuary

The Dongting Lake Estuary is migration pathways for some river-lake migratory and semi-migratory fishes. In the present study, an annual survey of fish was conducted from January to November 2018 covering a total of 6 sites in Dongting Lake Estuary. A total of 57 freshwater species and subspecies belonging to 5 orders and 10 families were recorded. The catches at the Dongting Lake Estuary were mainly composed of Lake settled fish. The biomass of Cyprinus (Cyprinus) carpio Linnaeus was the highest, accounting for 25.53% of the total catches, followed by Hypophthalmichthys molitrixs, Culter alburnus Basilewsky and Ctenopharyngodon idellus, accounting for 10.41%, 8.99% and 7.10% of the total catches, respectively. The four major domestic carps accounted for 26.13% of the total catch. The range of richness of species varied between 40 and 51 species. The trend was fewer species in spring, with the arrival of summer and autumn gradually increasing, peaking at the turn of summer and autumn, and then gradually decreasing with the arrival of winter, to the lowest in spring. The Shannon, Simpson, Pielou and Margalef indices showed the consistent trends with richness of species.

Effects of Rice-Fish Co-culture on Oxygen Consumption in Intensive Aquaculture Pond

Rice-fish co-culture has gained increasing attention to remediate the negative environmental impacts induced by intensive aquaculture. However, the effect of rice-fish co-culture on oxygen depletion has rarely been investigated. We constructed a rice-fish co-culture system in yellow catfish(Pelteobagrus fulvidraco) and freshwater shrimp(Macrobrachium nipponense) ponds using a new high-stalk rice variety, and conducted a field experiment to investigate the effect of rice-fish co-culture on water parameters and oxygen consumption. The results showed that rice-fish co-culture reduced the nutrients(total nitrogen, ammonia-N, total phosphorous and potassium) and the dissolved oxygen content in fish and shrimp ponds. However, they showed similar seasonal change of dissolved oxygen in the water of fish and shrimp ponds. Rice-fish co-culture reduced the total amount of oxygen consumption and optimized the oxygen consumption structure in pond. The respiration rates in water and sediment were significantly reduced by 66.1% and 31.7% in the catfish pond, and 64.4% and 38.7% in the shrimp pond, respectively, by additional rice cultivation. Rice-fish co-culture decreased the proportions of respiration in sediment and water, and increased the proportion of fish respiration. These results suggest that rice-fish co-culture is an efficient way to reduce hypoxia in intensive culture pond.

Investigation and Preventive Measures of Fish Parasites in Huaihua City

The losses caused by outbreaks of various diseases in aquaculture intensive farming are becoming more and more serious. Fish diseases have become one of the problems that constrain the healthy development of aquaculture. Among them,fish parasitic diseases have also caused some losses to the aquaculture industry. In this paper,17 species of fish parasites in Huaihua area,belonging to 15 genera in 13 families of 13 orders,are reviewed. In particular,the 10 kinds of fish parasitic diseases that are more harmful to farmed fishes are described in detail in order to provide a basis for the prevention of fish diseases in the future.

Estimation of Mercury Intake from Consumption of Fish and Seafood in Russia

Data on the mercury concentration in freshwater and marine fish and seafood on the territory of Russia are presented. The level and pattern of the fish and seafood consumption in various regions of Russia are found from the analysis of open statistics. Regions with the maximum and minimum consumption of fish products are established. Mercury intake from these products in a human organism is calculated. It is shown that at the current level and pattern of the diet in Russia fish cannot be a source of high mercury concentrations in a human organism.

The Ecological Balance of the Fish Community in an Aging Reservoir

Reservoir fishes contribute significantly to freshwater fish resources in Nigeria. The composition, size variation and relative abundance of fishes in Opa reservoir, Southwest Nigeria, were investigated to establish the ecological balance of the various trophic groups of fishes in the reservoir. The study was carried out in view of recent reports on the decline in the quality and quantity of water in the aging reservoir. Fishes were collected from the reservoir monthly for twelve months using monofilament gill nets and wire cages.? The fishes were identified to species level and the ecological balance of the fish community was calculated as a ratio of the forage to the carnivore groups by number and by weight. Data were subjected to statistical analysis using the Stata 13 software. 1915 fishes belonging to 17 species and 10 families were collected from the reservoir. The fish composition was dominated by the family cichlidae, with its 7 species accounting for 89.8% of the total catch. There were 2 species of clariidae, which made 6.2% of the total catch. The ecological balance of the fish community was 3.4 (by number) and 6.2 (by weight). The result obtained revealed that the fish community in the reservoir is ecologically balanced.Comparative analysis of the fish composition of the Opa reservoir with reports from other reservoirs in Southwest Nigeria showed that the reservoir has more fish species than most of the other reservoirs around. The study concludes that the reservoir still supports a rich, diverse and ecologically balanced fish community. It is recommended that the management of these fish resources should be key in the holistic management of the aging Opa reservoir.

Metazoan Parasites of <i>Geophagus proximus</i>, a Cichlidae Fish from the Eastern Amazon (Brazil)

The present study investigated the fauna of metazoan parasites of a Geophagus proximus population from the lower Tapajós River, in the state of Pará, northern Brazil. A total of 137 monogeneans were collected from the gills of G. proximus, including Sciadicleithrum kritskyi, Sciadicleithrum paranaensis and Sciadicleithrum geophagi, while 119 Raphidascaris (Sprentascaris) lanfrediae nematodes and 28 metacercariaes of digenea undetermined were collected from the intestine. Hosts harboring four species of parasites were predominant. The parasites had an aggregated dispersion pattern. The present study represents the first record of S. geophagi parasitizing G. proximus, increasing the geographic distribution of these parasite species to the Tapajós River basin.

江苏省淡水渔业碳汇强度和经济价值估算

根据2014—2023年江苏省淡水渔业养殖产量和捕捞产量数据,计算淡水渔业碳移出量和碳汇价值,并讨论了江苏省碳汇渔业发展面临的问题及对策建议。结果表明,10年间,江苏省淡水养殖碳移出量为21.55万~24.13万t,碳移出总量为226.41万t,占比较高的有鲢、鳙、鲫、草鱼、虾和河蟹;淡水捕捞碳移出量为2.17万~4.07万t,碳移出总量为34.67万t,鱼类、甲壳类和贝类分别占比为66.38%、14.54%和17.36%。根据碳汇市场价格100元/t来计算,养殖碳汇和捕捞碳汇价值年际变化分别为7908.85万~8855.71万元和796.39万~1493.69万元,江苏省淡水渔业碳汇价值合计为9.58亿元。江苏省淡水渔业养殖碳移出量及碳汇价值大于捕捞碳移出量及碳汇价值。

广东省内陆江河鱼类多样性

广东省地属热带和亚热带季风气候区,是我国鱼类资源丰富且社会经济最为活跃的地区之一,其鱼类生物多样性受到较大威胁。在近十几年调查的基础上,系统整理了广东省珠江水系、粤东水系和粤西水系14条河流(区域)的鱼类物种名录,并对其种类组成和分布进行了分析,利用聚类和排序方法探究了广东省内陆江河鱼类的空间分布格局。结果表明,广东省内陆江河共记录有鱼类351种,隶属于21目74科207属。其中,广东省特有鱼类13种,国家重点保护鱼类8种,河海洄游鱼类10种,淡水珍稀濒危鱼类28种,在珠江、粤东和粤西水系均有分布的广布种有52种。根据聚类和排序分析结果,可将14条河流(区域)分为5组:珠江水系和韩江鱼类种类较为相似分为一组;粤西水系和粤东的螺河、赤石河、黄江鱼类种类较为相似分为一组;粤东的黄冈河、榕江和练江各单独为一组。相似性分析结果显示,各组之间鱼类种类组成差异显著(r=0.937,p=0.001)。广东省江河鱼类中,2010年之后出现的种类有223种(含外来种群),约有39%的历史土著种类未出现,土著鱼类资源明显衰退。鱼类栖息地生境破坏、外来种群入侵等是鱼类多样性下降的主要威胁因素。未来需要加强保护区的建设和管理,防控外来种群的扩张,最重要的是从保护鱼类栖息地的角度进行水资源的开发与管理。

土臭素对淡水鱼品质的影响及控制策略研究进展

水产品味道鲜美,营养丰富,是人类摄取食物蛋白的重要来源。但以土腥味为代表的特殊异味在淡水养殖的鱼类中经常出现,不但影响水产品的风味,更降低了消费者的消费意愿,制约着水产品养殖行业的稳定发展。而科学控制和预防水产品中的土腥味是保障水产品质量的重要手段,对满足产业需求具有重要意义,仍需深入研究。本文综述了水产品中以土腥味为典型代表的特殊异味,探讨了以土臭素为代表的异味物质在水产品中造成土腥味的机理,并结合目前控制土腥味的常用方法,对未来水产品异味防控发展趋势进行展望,以期消除水产品中的异味物质,尤其是淡水养殖的水产品中存在的土腥味。

高效液相色谱-质谱法测定淡水鱼中地西泮

建立高效液相色谱-质谱法测定淡水鱼中地西泮。样品用乙腈提取,采用Florisil填料和氨基填料净化,当Florisil填料和氨基填料的质量比为2∶3时,能够有效地吸附淡水鱼基质中的脂肪、脂质和蛋白质等杂质,降低基质效应,提高质谱响应的信噪比。地西泮的质量浓度在0.05~20 ng/mL范围内与色谱峰面积线性关系良好,相关系数为0.9996,检出限为0.15μg/kg,定量限为0.5μg/kg。空白样品加标回收率为84.2%~95.5%,测定结果的相对标准偏差为5.25%~6.83%(n=6)。该方法快速准确,基质效应小,能够满足水产品中地西泮的测定要求。