Search

Mass mortality of Pangasianodon hypophthalmus in cultured earthen pond was investigated. Infected P. hypophthalmus were characterized by number of clinical signs such as abnormal swimming behaviour, skin lesion, and local hemorrhages. Moribund samples were collected from Karnataka to investigate the etiological as well as histopathological changes. The causative agents of the diseased pangasius were identified as Aeromonas hydrophila using specific selective media, polymerase chain reaction (PCR) technique and through scanning electron microscopy (SEM). The amplified DNA product was 130bp for haemolysin genes of A. hydrophila. Scanning electron microscopy revealed straight rods with single polar flagellum of A. hydrophila. Histopathogical studies of different organs of diseased P. hypothalamus revealed cellular alteration such as necrosis and hemorrhages in the gill and liver, tubular degenerations in the kidneys, splenitis accompanied with hemosiderosis in spleen. Additionally, there was sloughed necrotic debris in intestinal lumen with increase in goblet cell number. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the crowding and handling stress with increased cortisol production, its effect on growth and ontogeny of humoral immunity in Catla catla. Fishes were stressed at different stocking densities (T1, T2, T3 and T4) in crowding stress and were monitored for various parameters including length, weight, serum cortisol and immunoglobulin. In comparison to low stocking density group T1 (3000/ m²), high stocking groups (T2, T3 and T4) showed reduction in both average length and weight on 6th day onwards up to 40th day. The results of T4 (18000/m²) showed drastic reduction up to 12th day and died afterwards. Similarly, in handling stress fishes were stocked in six hapas at equal densities (3000/m²) with different stress (HS1, HS2, HS3, HS4, HS5 and HS6) revealed a decrease in average length and weight in comparison to control throughout the study period. Serum cortisol levels were significantly elevated (P<0.05) in higher crowding and handing stress groups. The results of ELISA for crowding stress showed that immunoglobulins were detectable in the spawn from 3 days post hatching (DPH). The immunoglobulin levels decreased till 18 DPH in T2, T3 and T4 groups, although the levels were significantly higher (P<0.05) in lower stocking density group (T1). In response to handling, all the stressed groups showed significant decrease (P<0.05) in immunoglobulin production in comparison to control at 18 DPH onwards. A slow recovery was observed on 40th day, although the immunoglobulin levels in stressed groups were remained lesser than the control. [ABSTRACT FROM AUTHOR]

A four month survey was conducted in twelve fish markets of Narsingdi Sadar, Sylhet Sadar and Moulvibazar Upazila of Bangladesh. The survey was conducted from September to December 2020in attempt to understand the current status of threatened fish species availability in those localities of Bangladesh. Fish markets were visited fortnightly. In Narsingdi Sadar fish markets, one (01) fish species of critically endangered, ten (10) endangered fish species and nine (09) vulnerable fish species were observed. In Sylhet Sadar fish markets one critically endangered fish species, eight endangered fish species and ten vulnerable fish species were found. Fish markets surveyed in Moulvibazar were observed with two critically endangered, eight endangered and five vulnerable fish species. Availability and price of fishes varied in all surveyed markets. Some conservation methods and consumers knowledge on awareness could improve the availability of endangered fishes. [ABSTRACT FROM AUTHOR]

Hypselobarbus jerdoni is an important medium-sized barb, indigenous to central Western Ghats, with an aquaculture potential and of conservational value. The aim of this study was to use mithochondrial DNA (mtDNA) COI and 16SrRNA genes as a supportive tool to precisely identify the two sister species, H. jerdoni and H. pulchellus, which show a lot of variation in meristic characters such as the number of lateral line scales. DNA barcoding included Cytochrome oxidase subunit I (COI) and 16SrRNA genes were done for representatives from different groups (sixty-two number of fishes) of Lateral line scales (Lls) counts. The results showed that there was no difference among the specimens based on DNA barcoding (COI and 16SrRNA genes), but there was a difference among them based on the number of llsc. This study reveals the use of llsc for the identification of these two sister species is questionable. [ABSTRACT FROM AUTHOR]

The truss network system was used to investigate the morphometric differences among three different life stages (Juvenile, sub-adult and adult) of Orange fin barb,Hypselobarbus jerdoni (Day 1870) from the Netravathi river. Truss network system of 14 landmarkswas interconnected to yield 91 distance variables. The principal component analysis (PCA) was employed for determining the morphometric variations. Four principal components were extracted through PCA explaining 99.864% of the total variance in samples. Again, the factor analysis of the transformed variables explained 98.24% of the total morphometric variation with percentage contribution of 93.543% and 4.70% on the first and second factor, respectively. The results acquired from Factor analysis (FA) and truss network system was that the maximum variations were dependent on the distance from i) anterior attachment of dorsal membrane from caudal fin to end of anal fin, ii) anterior attachment of dorsal membrane from caudal fin to insertion of pelvic fin, iii) anterior attachment of dorsal membrane from caudal fin to insertion of pectoral fin, iv) anterior attachment of dorsal membrane from caudal fin to end of operculum. The present study providesa useful insight on the application of truss analysis in the shape variationamong three different life stages of H. jerdoni. [ABSTRACT FROM AUTHOR]

An alternative approach to manage fish health that is fast gaining attention in the aquaculture industry is probiotics, a microbial intervention approach. Probiotics have shown that they can help to increase fish growth by enhancing the feed conversion efficiency, as well as confer protection against harmful bacteria by different modes of action. The present paper shows the current knowledge of the use of probiotics in aquaculture, particularly focusing on their modes of action such as spatial and nutritional emulation, inhibitory metabolites, immunomodulation and stress-alleviating mechanism. [ABSTRACT FROM AUTHOR]