Tail and fin rot disease (TFRD) is a big issue in the production of spotted snakehead, Channa punctata Bloch. The aims of the present study were to isolate and identify the bacterial pathogen causing TFRD, to detect histopathological changes in tissues (fin, tail, liver, and kidney), and to ascertain the antibiotic sensitivity pattern of the isolate. Out of six bacterial isolates, only the isolate DJ1990 was found to be the causal candidate of TFRD in C. punctata. Identical histopathological changes were detected in tail, fin, liver, and kidney under light and scanning electron microscope in both collected diseased fish and artificially infected fish. The isolate was identified as Pseudomonas aeruginosa strain DJ1990 (National Center for Biotechnology Information Ace. No. KX709967) based on the biochemical characterization tests and 16S rDNA sequence‐based phylogeny analysis. Artificial challenge test demonstrated that the strain DJ1990 was highly virulent (100% mortality at 48 h of postinjection period at the concentration of 1.5 × 107 CFU/g of body weight) for C. punctata. The isolate exhibited sensitivity to the broad‐spectrum antibiotics but was resistant against aztreonum. To the best of our knowledge, this is the first report of P. aeruginosa as a TFRD‐causing candidate in C. punctata.

The intent of this current exploration is to examine the natural convective magnetohydrodynamics (MHD) mass transfer flow past an infinite vertical porous plate implanted in a porous medium with thermal diffusion and chemical reaction. An analytical solution for momentum, energy, and concentration equations is achieved by implementing the perturbation method. A uniform magnetic field is installed orthogonally with the plate and the fluid undergoes a normal suction velocity with the consideration that heat flux at the plate is constant. In contemplation of recording the influence of different nondimensional parameters and deliberating the flow characteristics, the computational aftermath for fluid velocity, temperature, and species concentration is portrayed graphically. Investigations divulge the fact that the increase in thermal diffusivity causes hefty falls in the temperature field and improves the concentration of the fluid. Again it is also noted that the fluid velocity and species concentration dwindle as a result of a high rate of consumption of species. The solutions obtained in this study are attained asymptotically.

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Channa punctata (freshwater murrel) is an economically important fish species in Asian countries, including India. The present investigation demonstrates the pathogenic effects of Pseudomonas aeruginosa DJ1990 on the scales of fresh water C. punctata through optical and scanning electron microscopy. In order to determine the adverse effects of P. aeruginosa DJ1990, fish were exposed to different doses of bacterial load and sacrificed at 12 h interval up to 72 h of post-infection period. The light microscopic and electron microscopic examination of C. punctata scale clearly disclosed the bacterial invasion and concomitant destruction of the scale structure such as uprooted damaged lepidonts and dispersal of chromatophores. In the present study, it was observed that the advent of anomaly in scale structure (chromatophore dispersion, circuli damage, circuli disorganization, lepidontal breakage, lepidontal uprooting, lepidontal sockets exposing, lepidont displacement and scale loosing) was dependent on the pathogen loads and time of expose. Till date, several studies have been conducted in the field of fish pathology; however, scales are given less priority in comparison to hematopoietic organs. To the author's best knowledge, it is the first report describing the effect of bacterial pathogen on the scale of a fish species, C. punctata.

The motive behind this investigation is to examine the unsteady magnetohydrodynamics free convective fluid flow with heat and mass transfer of a viscous, incompressible flow past a moving upright plate in a porous medium with radiation, chemical reaction, arbitrary thermal, and solutal ramped condition. An analytical solution for momentum, energy, and concentration equations is accomplished by implementing the Laplace transformation technique. The influence of different nondimensional parameters on fluid velocity, temperature, and concentration along with skin friction and rate of heat transfer as well as mass transfer at the plate are exhibited graphically. It can be spotted that both the concentration and temperature field decrease for rising values of the ramped parameter, radiation parameter, chemical reaction parameter, and Schmidt number. Moreover, it is detected that the fluid velocity drops in the case of the isothermal plate, and velocity upsurges for the ramped plate temperature. Investigation simulates that the rate of heat transfer, as well as rate of mass transfer, is escalated on hiking radiation parameter.