Immunological and molecular diagnostic techniques in fish health: present and future prospectus.

Fish health management is critical to aquaculture and fisheries as it directly affects sustainability and productivity. Fish disease diagnosis has taken a massive stride because of advances in immunological and molecular diagnostic tools which provide a sensitive, quick, and accurate means of identifying diseases. This review presents an overview of the main molecular and immunological diagnostic methods for determining the health of fish. The immunological techniques help to diagnose different fish diseases by detecting specific antigens and antibodies. The application of immunological techniques to vaccine development is also examined in this review. The genetic identification of pathogens is made possible by molecular diagnostic techniques that enable the precise identification of bacterial, viral, and parasitic organisms in addition to evaluating host reactions and genetic variation associated with resistance to disease. The combination of molecular and immunological methods has resulted in the creation of novel techniques for thorough evaluation of fish health. These developments improve treatment measures, pathogen identification and provide new information about the variables affecting fish health, such as genetic predispositions and environmental stresses. In the framework of sustainable fish farming and fisheries management, this paper focuses on the importance of these diagnostic techniques that play a crucial role in protecting fish populations and the aquatic habitats. This review also examines the present and potential future directions in immunological and molecular diagnostic techniques in fish health.

Clostridium perfringens from fresh water fish of Kashmir Himalaya and their aquatic environment: Toxinotyping and phylogenetic analysis.

Clostridium perfringens is a common anaerobic foodborne pathogen known to produce >20 toxins. In nature, this bacterium has 7 different toxinotypes (A-G) based on the presence of its 6 main toxins. The present study examined the occurrence of different toxinotypes of this bacterium in the ichthyofauna and aquatic environments of Kashmir Himalayan lakes, India. A total of 510 samples (210 water; 150 each of common carp and snow trout) were collected from 3 different lacustrine habitats (Dal, Anchar and Nigeen Lakes) of the region. By performing 16S rRNA PCR test, it was observed that all 210 water samples and 80 (26.66%) of 300 fish samples tested for this specific bacterial species were positive. Then by using multiplex-PCR targeting six virulence genes of C. perfringens, it was confirmed that all the 290 isolates from water and fish samples were positive for Toxinotype A, as only cpa toxin gene was amplified. Phylogenetic analysis of the amplified gene and its amino-acid sequences revealed 95%-98% homology with analogous sequences of this bacterial strain reported from China, Egypt and India. The study documents the existence of C. perfringens toxinotype A in the ichthyofauna of Kashmiri Himalayan lakes, entailing that fish can likely act as transmission medium for C. perfringens food poisoning to humans via food.

Distribution of Helminth Parasites in Intestines and Their Seasonal Rate of Infestation in Three Freshwater Fishes of Kashmir.

The present study was undertaken to determine the incidence of helminth parasites in fishes with special reference to water quality parameters in Dal Lake and River Jhelum and correlate the observations. Water, fish, and parasite samples were collected during different seasons from various sites and processed. Three fish species, namely, Schizothorax niger Heckel 1838, Schizothorax esocinus Heckel 1838, and Schizothorax curvifrons Heckel 1838, were recovered from these water bodies. The physicochemical parameters temperature, dissolved oxygen, pH, and free carbon dioxide showed variation vis-à-vis the season and location of the stations in water bodies. Acanthocephalan parasite Pomphorhynchus kashmirensis Kaw 1941 (27.47%) and two intestinal cestodes Bothriocephalus acheilognathi Yamaguti 1934 (30.63%) and Adenoscolex oreini Fotedar 1958 (32.43%) were recovered from all the three species of Schizothorax. All the three parasites showed higher prevalence during summer and the least prevalence during winter. Parasitic infections were prevalent more in male fishes compared to females. The presence of the parasites had reduced the condition coefficient of the infected fishes in both water bodies. The study also showed that some of the physicochemical features showed a significant positive correlation with the prevalence.

Dimethoate Induced Behavioural Changes in Juveniles of Cyprinus carpio var. communis under Temperate Conditions of Kashmir, India.

The present study was designed to investigate acute toxicity of dimethoate on juvenile Cyprinus carpio var. communis. Fishes weighing 10 ± 2 gms were selected and mortality data was statistically evaluated by Finney's Probit Method. The 96-hour LC50 value for Cyprinus carpio was found as 1.1 ppm in static bioassay system. Mean values of physicochemical parameters of aquarium waters determined during bioassay depicted slight variation indicating that the mortality in aquarium fishes occurred due to pesticide exposure and not suffocation. Lab. temperature ranged from 12 to 13°C; water temperature ranged from 11 to 12°C; dissolved oxygen ranged from 3.90 to 4.56 mg/L; pH ranged from 6.90 to 7.05; total dissolved solids ranged from 2.66 to 3.0 × 10(3) mg/L, while CO2 remained at a constant value of 2.0 mg/L. The fishes elicited various behavioural responses such as uncoordinated movements, convulsions, excessive mucus secretion, and imbalanced swimming which ended in a collapse to the bottom of the aquarium. Prior to death, the clinical signs like scale erosion, pale body colour, and hemorrhagic patches over the body were noticed which became more vivid up to the termination of experiments. Results of the study indicate potential toxicity of dimethoate in fingerlings of common carp for which the natural waterbodies must be continuously monitored to reduce its impact across food chains.