Search

Background: An experimental study was conducted to examine growth performance and economic feasibility of Cyprinus carpio (Linnaeus, 1758) and Labeo rohita (Hamilton, 1822) vis-à-vis their improved strains viz. Amur carp and Jayanti rohu, in synchronously integrated rice-fish system at high altitude terraced paddy-fields (HATPF). Methods: The experimental fields were stocked with carp fingerlings (6.95±0.67 g) at a density of 0.6 no. m-2 having common carp (T1), rohu (T2), Amur carp (T3) and Jayanti rohu (T4) under monoculture system, common carp+rohu (T5) and Amur carp+Jayanti rohu (T6) under polyculture. The study period was 120 days (July to November, 2022). Result: The study recorded average weight gain of 55.72±5.58 g and 57.08±4.05 g in monoculture and polyculture systems, respectively. Amur carp performed significantly better (p less than 0.05) than other species/strains. Survival rate ranges from 72% to 85% with Amur carp and common carp recorded higher survival than rohu and its strain. Through integration, about 243.2 to 350 kg ha-1 of fish can be produced without supplementary feed and earn about Rs. 60,800 to Rs. 87,500 ha-1 in a single crop. Amur carp and common carp were found more suitable for rearing in integrated rice-fish culture system at HATPF.

Background: There is a gap that we will need to use innovative solutions to produce more food and nutrition. RAS is a continuous water-flowing system that can induce schooling behaviour, a phenotypic character seen in Asian seabass that could help cut down cannibalism at a certain level. Stocking density is one of the critical factors affecting the growth, survival and health status of animals, which can influence the antagonistic behaviour pattern, hierarchical phenomena and cannibalistic nature of Asian seabass during the early life stage. Methods: A 60-day trial was conducted to evaluate the effect of different stocking densities (70, 140, 210, 280 and 350 fish/m3) on biochemical and stress gene expression of Asian seabass (Lates calcarifer) reared in Recirculating Aquaculture System by following a completely randomized design with four replications. Result: The study found that fish reared at 350 fish/m3 had significantly higher haemoglobin and red blood cells. In the case of biochemical parameters, total protein, Albumin and Globulin were lower in 70 fish/m3 and Blood Urea Nitrogen, cholesterol and triglycerides were significantly higher in 350 fish/m3 treatment. The relative gene expression of HSP70, HSP90A and GST was significantly upregulated with the increasing stocking density. The study suggests that the rearing of Asian seabass at a stocking density of 70 fish/m3 in a recirculatory aquaculture system could improve the growth performance and metabolic and molecular activities of the fish.

Background: Ranaviruses are now emerging as serious pathogens for the amphibians, reptiles and fishes. The aim of this study was the determination of the susceptibility of goldfish (Carassius auratus L.) and tilapia (Oreochromis niloticus L.) to experimental infection with Koi ranavirus (KIRV). Methods: The experimental fishes were challenged with an infective dose of KIRV (106.8 TCID50/ml) by intraperitoneal injection (IP), while the control groups were injected with L-15 medium. Target tissues were collected from the experimental fishes infected with virus at 3, 7, 14, 21 and 28 dpi. Tissue samples were subjected to detection of KIRV by polymerase chain reaction (PCR), cell culture assay and histopathological technique. Result: This study reports no specific clinical signs and mortality due to virus infection during the experimental period. Experimentally infected goldfish and tilapia were tested positive for KIRV by PCR at 3 dpi, while target viral DNA was also detected in tilapia at 7 dpi by PCR. However, specific DNA of KIRV was not detected in tissues of experimental fish sampled at later experimental study periods. Cell culture assay revealed no cytopathic effect in the Epithelioma Papulosum Cyprini (EPC) cell line at all sampling time points. Histopathological study revealed focal necrosis, shrunken glomerulus and detached epithelium of tubules in kidney tissue at 3 and 7 dpi in gold fish and melanomacrophage cells and focal necrosis of glomerulus and detachment of the epithelium of tubules in kidney tissue at 3 and 7 dpi in tilapia. Melanomacrophage centers and necrosis were observed in spleen tissues of goldfish and tilapia at 3 and 7 dpi. The challenge study indicated that goldfish and tilapia are not the targeted species for KIRV.

Background: This experiment was conducted to evaluate the effect of different stocking density on growth performance, survival, water quality and body indices of E.suratensis fingerlings for 90 days at PRFF, Pazhaverkadu. Methods: Three different stocking densities are 100, 200, 300 no of fishes/m3. The fingerlings of pearlspot, E.suratensis with an average body weight of 5.05±0.03 g were stocked at a rate of SD-1 (100/m3), SD-2 (200/m3) and SD-3 (300/m3) culture for a period of 90 days. Result: The growth parameters were found to significantly decrease with increasing stocking density in the biofloc rearing system. Result of Nitrite and nitrate concentrations were significantly lower in the BFT treatment with lower stocking density than in higher stocking density (P less than 0.05). The highest mean body weight gain recorded in SD1 (42.37±0.04 g) followed by SD2 (29.98±0.08 g) and SD3 (20.85±0.06 g). BFT significantly increased fish specific growth rate and net yield. There was no significant difference in hematology analysis (in terms of white blood cell and red blood cell counts, hemoglobin and hematocrit levels), total superoxide dismutase activity of fish between different stocking density (P greater than 0.05). Second-order polynomial regression analysis of weight gain against pearlspot culture under lower stocking stocking density (100/m3) indicate that biofloc technology culture with lower stocking density can improve the growth performance and immune response and also the maintenance of good water quality and improvement of feed utilization of pearlspot.

Background: Successful and sustainable culture of finfish and shellfish depends on the use of nutritionally balanced, low-cost and eco-friendly feeds. This experiment was conducted to evaluate the effect of dietary supplementation of lysine and methionine on the growth and physiological responses of juvenile pearlspot, Etroplus suratensis. Methods: Fingerlings with an average initial body weight of 8.7±0.04 g were distributed to the 300 L FRP tank (n=30 pieces/tank). The pearl spot fingerlings were fed with isonitrogenous (25% Crude protein) feeds supplemented with methionine (1.8, 2.2 and 2.6 g/100 g of diet) and lysine (0.5, 0.9 and 1.3 g/100 g of diet). The growth performance and physiological response of the fishes were assessed. The feeding trial was conducted for a period of 60 days. Result: The methionine supplemented diets at 2.2 g/100 g (T2) and Lysine supplemented diet at 0.9 g/100 g (T5) yielded the best results within the treated groups in terms of average body weight gain, FCR (feed conversion ratio), SGR (specific growth rate), PER (protein efficiency ratio) and FER (feed efficiency ratio). The maximum mean body weight gain recorded in methionine supplemented diet was 20.68±0.20 g in T2 and the maximum mean body weight gain recorded in lysine supplemented diet was 19.6±0.15 g in T5. The mean body weight gain in control was recorded as 12.12±0.20 g. The present study revealed that methionine incorporation at 2.2 g/100 g (T2) and lysine incorporation at 0.9 g/100 g (T5) resulted in better growth performance of the pearl spot Etroplus suratensis fingerlings. Results of challenge tests confirmed that V. anguillarum could act as a primary pathogen for pearlspot reared in freshwater. In the present study, the Hb, RBC, MCV, MCH and MCHC were also affected by dietary methionine and lysine supplementation and were found significantly (p less than 0 .05) higher in fish fed methionine at 2.2% and lysine at 0.9% of diet, indicating that dietary methionine and lysine supplementation activates immune response and promotes fish health. Second-order polynomial regression analysis of weight gain against dietary methionine and lysine levels indicated that the optimum dietary methionine and lysine requirement for maximum growth and feed utilization of pearlspot fingerlings was methionine at 2.2% and lysine at 0.9%.

Background: Pulicat lake is the second largest brackish water lagoon in the country, lying partly in Andhra Pradesh and Tamil Nadu states along the Coromandel Coast of South India. The present paper gives information on occurrence, habitat preference, trophic level, human utility and fishery status of finfish and shellfish species of the Pulicat Lake. Methods: An extensive survey was conducted on finfish and shellfish diversity of Pulicat Lake from November 2019 to March 2021, selecting four fish landing centres viz, Pazhaverkadu, Arambakkam (fishing villages in Tamil Nadu), Venadu and Vatembedu (fishing villages in Andhra Pradesh) situated along the Lake. Result: In the present study, A total of 145 species including species of finfishes (95), prawns (8), crabs (7) and 35 molluscs (35) were documented from the Lake. Among the four selected landing centres, the highest diversity was observed in Pazhaverkadu, registering 143 species followed by Arambakkam (123), Vatembedu (85) and Venadu (77).

Background: The pesticides are known to adversely affect the quality of water and create hazards for aquatic life that results in severe damage to non-target freshwater organisms including fish. Among them, the organophosphorus pesticide, chlorpyrifos (CPF) is one of the most commonly used pesticides for controlling various kinds of pests in agriculture. Pesticides after entering in to the body of fish bring about histopathological and biochemical changes in different target and non-target organs. Hence, the present study aimed to investigate the toxicity effects of Chlorpyrifos (CPF) and associated histopathological changes in the gill, liver and kidney of the Mozambique Tilapia, Oreochromis mossambicus under the acute toxicity concentrations. Methods: Static bioassay was carried out for Chlorpyrifos with Oreochromis mossambicus as test animal for a period of 96 hrs as per standard methods and LC50 values were calculated through Probit analysis. The fishes were exposed to five acute concentrations (0.033, 0.066, 0.132, 0.264 and 0.528 ppb). The gill, liver and kidney tissues were collected from the fishes exposed to the pesticide and standard histology protocol was followed to investigate the histopathological changes. Result: The histological changes observed in the gill included lamellar aneurysm, curling of secondary lamellae, shortening of the secondary lamellae, hypertrophy of epithelial cell, fusion of secondary lamellae, deformation of the cartilage core, blood congestion, collapsed secondary lamellae, excessive mucus secretion, disorganization of the secondary lamellae, haemorrhage at primary lamellae, necrosis, haemorrhage at secondary lamellae. The most common histopathological changes in the liver were characterized by cellular necrosis, degeneration of hepatocytes, nuclear degeneration, fat deposition, rupture of nucleus, hypertrophied hepatocytes, blood congestion, blood sinusoids, cellular hypertrophy, increased pycnotic nucleus, cirrhosis and hemosiderosis. Further, histological changes like appearance of dilated lumen, hypertrophied epithelial cells, severe haemorrhage, blood congestion, melanomacrophage aggregation, narrowing of lumen, degenerated tubule, degenerated glomerulus, shrunken glomerulus and distended glomerulus were observed in the kidney. Thus, it is evident from the present study that Chlorpyrifos can be a potential toxicant affecting the fishes at tissue level on dose and time dependent manner which are expected to affect the other physiological processes in the long run.

In the present study, induced breeding of endemic barb, Dawkinsia filamentosa was carried out using three different synthetic hormones namely Human chorionic gonadotropin (HCG), WOVA-FH and Ovatide at different (0.3, 0.5, 0.7 and 0.9 ml/Kg) doses. All synthetic hormones showed good performance at 0.7 ml/kg body weight. Comparatively WOVA-FH showed better performance with higher number of spawned eggs (1405±5.74 nos/female) and hatching rate (90±0.6%). The study concluded that WOVA-FH at 0.7 ml/kg is an ideal for induced breeding of D. filamentosa. Fertilised eggs were golden in colour with an orange tinge. Hatching took place 34- 36 hrs (26±0.50C) of post fertilization. Yolk sac remained up to 60 hrs of post hatching. Complete developmental stages of D. filamentosa from egg to adult were recorded in captive condition. The present study aids in introducing hatchery-bred seeds of valuable indigenous fish Dawkinsia filamentosa into the ornamental fish trade. Availability of hatchery seed may reduce the wild exploitation and contributes to the conservation of the natural resources.