Assessing Heavy Metal Bioaccumulation in Freshwater Fish at the Gingee River in Puducherry, India

Heavy metal bioaccumulation was investigated in fish from the Gingee river in Vadamangalam and Ariankuppam in the Puducherry area, including mercury (Hg), zinc (Zn), and copper (Cu) (Cu). According to the study, heavy metal concentrations in sediments were more significant than in water. Depending on the season, the amount of heavy metal played at each location changes. Heavy metal bioaccumulation was seen in river fish. Metal concentrations have been detected in the following order: sediment > fishes > water.

THE STUDY OF THE BIOLOGY OF THE ROACH RUTILUS RUTILUS CASPICUS (JAKOWLEV, 1870) IN THE KRAYNOVSKY COAST OF THE CASPIAN SEA

The offshore zone of the western coast of the Caspian Sea is one of the most highly productive. Of the 63 species of fish that live in the Caspian Sea, 34 species are found on the Krainovsky coast, 42 % of which are carp. The most numerous is the roach Rutilus rutilus caspicus (Jakowlev, 1870), which makes up 50–86 % of the number of semi-passerine and river fish. The article presents the results of studies of the peculiarities of the biology of the roach Rutilus rutilus caspicus of the Krainovsky coast of the Caspian Sea. The roach is noted in the catches constantly. Her age in the networks ranges from 2 to 10 years. The share of 3-5-year-olds accounts for 81 %. Females in catches make up 66 %, males - 34 %. The parameters of the Bertalanfi equation are characterized by the following values: L =38.8 cm, K = 0.12, t° = -2.67. The fecundity of the roach on average is 30.2 thousand eggs and tends to increase with increasing length and weight of the fish. As the roach grows, the composition of its food changes significantly. The maximum fed roach length from 10 to 20 cm.

Effect of lactic acid and lysozyme on river fish fillets during cold storage

Presented work evaluated how quality of catfish fillets is affected by treatments using lactic acid or lysozyme in combination with chlorine. Fish fillets without skin were consecutively immersed and washed in 100 ppm chlorine solution and sprayed with 2.5% lactic acid or 0.5% lysozyme solution. Control samples were only washed with water at the same time. Samples were stored at 2 °C for 10 days in vacuum packaging. Parameters of pH, firmness, surface color and microbial cell counts (cfu/g) were measured on the 1st, 4th, 7th and 10th days. Especially the latter had high importance from the point of view of food safety. Catfish fillets shown decreased survival of microorganisms as a result of treatment. Lysozyme and lactic acid achieved 1.8 and 2.4 log cfu/g reduction, respectively. Lower cell counts were observed for all treated samples compared to control during 10 days. Chlorine in combination with lactic acid achieved the best efficiency. The results are promising and suggest that combined treatment is able to improve safety by controlling microorganisms on fish fillets during cold storage.

Diversity of Fish Species in Several Sites Along the Brantas River East Java Indonesia

The purpose of this study is to describe the presence of species diversity and composition in Bratas River. Fish sampling was conducted in dry and rainy seasons in five locations, namely Batu City, Blitar City, Tulungagung regency, Jombang Regency, and Mojokerto Regency, East Java. This study collected 295 individual fishes belonging to 12 species. The 162 individuals were obtained in the dry season, while 133 individuals were captured in rainy season. The most dominant species was mujahir (Oreochromis mosambica) followed by keting (Mystus paniceps) and kutuk (Channa striata). The fish abundance significantly varied among study sites, while that of species richness and diversity did not differ significantly. Fish diversity in high elevation was the lowest, while that in relatively middle elevation was the highest. Compared to the previous report, fish species diversity in Brantas was decreasing, some species were not found. Three species were considered as exotic include Oreochromis mosambica, Clarias batracus, Oreochromis niloticus.

The role of anthropogenic impact and natural habitat conditions in the reproduction of semi-passable and mass river fish of the lower reaches of the Volga River according to retrospective data

A retrospective review of the main factors that caused the decline in the reproduction of semi-passable fish in the lower reaches of the Volga River is given. Long-term data on the yield of juvenile semi-passable and river fish are presented, on the basis of which the current state of natural reproduction of roach, carp is estimated as low; bream, bluefin and perch — satisfactory; crucian carp, gaster and rudd — safe. Overregulation of the Volga River flow near Volgograd violated the natural conjugacy of water and temperature regimes. In the regulated period, the timing of the onset of spawning temperature in most cases is ahead of the flooding of the strips. The lag of the delta spawning grounds begins when the runoff is less than 120 km³ and reaches the maximum values (up to 27 days) in years with extremely low water content. The delay in flooding of spawning grounds in conditions of unsatisfactory water content leads to the accumulation of producers in limited areas of strips and simultaneous spawning of fish with different ecology. This leads to increased food competition of the larvae and reduced survival. After the flow was regulated, the rates of rise and fall of the hollow waters increased by 2 times, the hatching of the larvae, as a rule, coincided with the onset of the flow of the hollow waters. The mass removal of larvae into the delta watercourses at the early stages of ontogenesis, due to their lack of viability in river conditions, leads to a decrease in the productivity of spawning grounds. In the modern period (2003– 2019), due to the predominance of unfavorable hydrological regime, the duration of high water and flooding of the poloi years, and in order to clarify the yield of juvenile fish in the lower reaches of the Volga, its accounting was carried out not only in the poloi of the delta, but also in the coastal watercourses (where a large number of larvae and fry that rolled off the poloi and from local spawning), in the kultuch zone and on the poloi of the lower zone of the Volga-Akhtuba floodplain.

Safety Analysis of Freshwater Fish

The results presented in this paper demonstrate that the microbial population in the hydroecosystem has seasonal variations. The bacterial contamination of water and fish in November was 140 and 11 times less than in July respectively. It was found that fish caught in natural reservoirs in the autumn-winter period had different dynamics in the development of postmortem changes in comparison with those caught in the summer period. Postmortem secretion of mucus was not as pronounced in autumn-winter as in summer. Postmortem rigidity on the contrary was pronounced; gill covers were tightly fitting; and spinal muscles were tensed and of dense texture. Storing fresh river fish at a temperature of 3-5°C for 24 hours did not lead to a change in sensory evaluation. Physic-chemical indicators corresponded to the values characterizing fresh, healthy fish. During storage, the bacterial contamination of fish increased by more than 100 times, while the maximum permissible number of microorganisms (5.0 × 104 CFU / g) was not exceeded. Keywords: fish, microbiological control, organoleptic and physic-chemical indicators