Gadadhar Dash

Myxobolus cerebralis infecting the brain of Heteropneustes fossilis (singhi) was identified morphologically, histopathologically and by molecular method captured from the beels of Raidighi, South 24 Parganas, West Bengal, India. Infection of M. cerebralis was uncommon in Heteropneustes fossilis brain. The infection rate was low to moderate. Microscopically Myxobolus parasites were detected in brain of Heteropneustes fossilis (singhi). Large plasmodia were localized within brain, causing severe necrotic changes and vacuolization. Inflammatory infiltrates agglomeration, nuclear hypertrophy, vacuolization, infiltration of blood cell and haemorrhages were extensively observed in the brain. Polymerase chain reaction (PCR) with primers specific for the family Myxobolidae was used to amplify an approximately 1600 base pairs (bp) long fragment of the 18S ribosomal RNA gene.

ABSTRACT A severe epizootic of bacterial diseases affected a number of commercial penaeid farms in Contai, Soula, Balisai and Digha regions of East Midnapur District, West Bengal, India in 2004. Histological and scanning electron microscopy (SEM) examination of affected Penaeus monodon showed massive infections in the hepatopancreas and partly in gills, pleopods and on shell. The affected shrimps had symptoms of vibriosis, gill disease, shell disease, red discolouration due to hepatopancreatitis etc. Shrimps with bacterial infection showed significant host inflammatory response in the form of hemocytic infiltration, granulomatous reaction and nodule formation. Histopathological observations revealed necrosis of hepato-pancreatic cells, thickened basal lamina and subsequent granulomatous encapsulation of the invaded tubules. Scanning electron microscopic (SEM) studies on shell diseased shrimp epithelial cells revealed signs of pathology due to bacterial infection. The normal SEM architecture of shell was totally lost and the shell had irregular indentations due to degenerative process. A large number of bacteria, which remain attached to the granular core of damaged epithelium of diseased shrimps were visible.

The research work was conducted to find out the prevalence or PFI and severity of monogenean parasites on Indian Major Carps in West Bengal fish farms. An investigation was made on Catla (Catla catla), Rohu (Labeo rohita) and Mrigal (Cirrhinus mrigala), from different parts of West Bengal. Approximately 505 fishes were observed in between June to December 2012 from different fish farms. Dactylogyrus sp. infest gill whereas Gyrodactylus sp. affect both skin and gill. Prevalence of Dactylogyrus sp. were high during August (PFI,83.45%) compared to June where PFI was only 4.5%. Similarly Gyrodactylus sp. showed high prevalence in August (PFI,28.88%) compared to it’s zero prevalence in June. Prevalence and severity of the infestation were also found to be related to different length group of the hosts. Labeo rohita was more susceptible to monogenean parasites. Infestation rate were more in small (1 to 10 cm) and medium (10.5 to 30cm) sized fishes, may be due to poor immune power compare ...

Although helminthic infection was quite common in Indian Major Carps, only a very few parasites among them are having Zoonotic potentiality. Only three Zoonotic strains Heterophys sp, Chlonorchis sp and Capillaria sp were identified from Indian Major Carps during the research work. These Zoonotic strains in particular regions were quite low as compared to other helminth sps. Catla catla were found to be more susceptible than Labeo rohita and Cirrihinus mrigala. Nematode infection was observed more in small size groups of fishes mainly in rainy season where as the prevalence of trematodes was more during summer in small size fishes also.

The study was conducted to collect and identify different parasites of Mystus gulio to determine the prevalence of helminths infestation in terms of month, seasons and length groups of fishes from different districts of West Bengal. The isolated parasites were Monogeneans, Digeneans, Cestodes, Nematodes and Acanthocephalans. The most dominant parasites in M. gulio were Acanthocephalans mainly observed in monsoon season. The larger length groups fishes were found to be more infected with parasites compared to smaller length groups. Three Acanthocephalans species including Pallisentis sp., Raosentis podderi and Acathogyrus sp. were found in host fish. Morphometric measurements of these three acanthocephalans parasites were observed during the study. Two way ANOVA was done to determine the significance of differences in Parasitic Frequency Index (PFI).

Thelohanellus caudatus infecting the caudal fin of carp Labeo rohita was characterized morphologically and by 18S rRNA gene sequence analysis. Infection of Myxobolus spp. and Thelohanelus spp. was more common in L. rohita gills with the parasitic frequency index of 66.67% and 50.00%, respectively. The prevalence of fin infecting Thelohanellus was 12.50%. The infection rate was low to moderate. The plasmodia on the caudal fin were small, white to pale yellow, elongated and 0.5–0.7 mm in length. The caudal fin of infected fish had up to 3 plasmodia, which contained about 50–60 spores each. Morphologically, Thelohanellus species closely resembled Thelohanellus caudatus. The comparison of 18S rRNA gene sequences of T. caudatus to other Thelohanellus spp. available in GenBank revealed only 72–78% homology. The T. caudatus (accession number KC865607) was clustered phylogenetically with the clade of freshwater myxosporeans. In the phylogenetic tree, T. caudatus formed dichotomy with T. hov...

The morphometric and molecular characterization of Thelohanellus catlae a new myxozoan belonging to genus Thelohanellus Kudo, 1933 (Myxosporea:Bivalvulida) infecting the gills of Catla catla were described in this study. The infection was observed as irregular, milky whitish, cyst-like plasmodia (up to 2.0-3.0 mm in diameter) attached to the gill filaments of the host fish. Each spore has a single pyriform polar capsule. Spores measured about 20.4±0.69 (19.3-21.4) × im long and 11.5± 0.63 (10.7-12.4) im wide. The polar capsule was 12.3±0.70 (10.7- 13.9) im long and 10.95± 0.28 (9.7-12.9) im wide. Sequencing of 18S rRNA gene of the new myxozoan revealed 98% sequence homology between the 18S rRNA gene of T.catlae. Phylogenetic analysis showed T. catlae within the clade of gill infecting myxosporeans and closed together with T. catlae. The importance of myxosporeans introduction to new locations along with infected cultured host is emphasized.

The present work was conducted to isolate and identify different parasites from Indian Major Carp (IMC) Catla catla. During the study period the severity of infection and Parasitic Frequency Index (PFI, %) were also estimated in terms of months, seasons and length groups of fishes. For the investigative purpose different districts of West Bengal were selected considering the potential of fishery resources. Approximately 300 fishes were observed during the entire period of observation. The parasite infested fishes were found to suffer mainly from respiratory manifestations, blackness of the skin and mortalities. The isolated parasites were Myxobolus, Thelohanellus, Trichodina, Dactylogyrus, Gyrodactylus, Nematodes, Argulus, Lernea and Chilodonella species. Besides these, developmental stages of different parasites were also found. Among these parasites Myxobolus, Dactylogyrus and Gyrodactylus showed the highest prevalence in winter. Remaining all parasites was found to be more during...

The fish juveniles surveys were conducted in Hooghly estuary near Sagar Island in Indian Sundarban in 2008 to study their composition, diversity, distribution and seasonal occurrence. A total of 65 species belonging to 27 genera under 20 families were identified from two stations of Hooghly estuary at Sagar Island, viz., Baguakhali and Chemaguri. Of the 20 families, Engraulidae represented highest diversity of 12 species, followed by Mugilidae (8 species), Chipeidae (7 species) and Gobiidae (6 species). The diversity of species was minimum during post-monsoon and maximum in pre-monsoon periods. The most doninant families were Engraulidae, Mugilidae, Culpeidae, Gobidae and Cynoglossidae. The composition and diversity fish juveniles in the Baguakhali was higher than that of Chemaguri in all seasons.

Prevalence and seasonal abundance of protozoan parasites in penaeid shrimp ( Penaeus monodon ) of high saline bheries of West Bengal was carried out for a period of 20 months from February 2000 to November 2001 covering two successive cropping seasons. The water quality parameters like temperature, hardness and salinity influenced the prevalence and distribution of parasites. These variables have definite impact individually or as a whole on the prevalence of parasites o f shrimp.The protozoan ectoparasites identified commonly were Zoothamnium sp, Vorticella sp, Epistylis sp and Acineta sp. The only endoparasite found was microsporidians ( Nosema sp) with low Parasitic Frequency Index (PFI). Monsoon was found to be the most favorable season for almost all the parasites ( Zoothamnium sp, Vorticella sp, Epistylis sp, Nosema sp) except Acineta sp, which showed it’s proliferation in summer season.

Aeromonas sobria has frequently been reported as a causative agent of motile Aeromonas septicemia (MAS) along with A. hydrophila in fish and other aquatic organisms. Till now there is lack of precise tool for early diagnosis of this disease. The aim of the present study was to fractionate and characterize the outer membrane protein (OMP) antigen of A. sobria by serological techniques so as to identify immunoreactive molecules that might be useful in preparing immunodiagnostic tools against A. sobria infection in goldfish. Eight fractions were isolated from the crude OMP antigen using Sephacryl S-200 and DEAE-cellulose chromatography. The highest seroreactivity was observed in the gel-permeated protein G1 which had an optical density (OD) of 0.72 nm, higher even than that of the crude OMP antigen, 0.63 nm. The serodiagnostic potential of G1 was assessed by using dip-stick ELISA. Therefore, fractionated antigen G1 (molecular wt 42-67 kDa) should be further studied in immunodiagnostic ...

Abstract Transportation of fish, although stressful, is an inevitable procedure in aquaculture practices. In this study, we investigated the changes in biochemical and haematological indices in advanced fingerlings of rohu, Labeo rohita in order to optimize the packing density as is imperative to avoid transportation stress and associated mortality . The fish (14.00–15.00 cm) were packed in sealed double layer oxygen packed polythene bags of 30 L capacity containing 7.5 L of water and transported for 2 h and 30 min in a motor vehicle at three packing densities, viz., 67 g L −1 , 134 g L −1 , and 201 g L −1 and transported from hatchery to Kolkata, India covering a distance of about 55 km. A cumulative mortality of 30% was recorded during and after transportation in fish transported at 201 g L −1 ; while the other two packing densities recorded no mortalities. Transportation and packing density induced stress affected the functioning of liver and kidney. The activities of transaminases and lactate dehydrogenase, breakdown of protein and creatinine phosphate, cortisol induced glucose production were significantly increased in advanced rohu fingerlings to cope with the energy demand posed by transportation and higher packing density stress. Low levels of dissolved oxygen and high levels of ammonia-nitrogen were noticed in different packing densities after transportation. The results suggested that the optimum packing density for advanced rohu fingerlings for 2–3 h duration of transport would be 134 g L −1 , which kept the stress at low levels. The serum alanine aminotransferase levels can serve as a good marker for fish liver health as the increment was more prominent when subjected to transportation stress.

Myxosporeans are best known for the diseases they cause in commercially important fish species. Identification of myxosporeans at the species-level is mainly based on conventional methods. The 18S rRNA gene sequence of morphologically identified Myxobolus orissae infecting the gill lamellae of mrigal carp Cirrhinus mrigala was characterized in the present study. The plasmodia of M. orissae were small, elongated and white to pale in colour. Phylogenetically, the 18S rDNA nucleotide sequence of M. orissae was clustered with other gill-infecting Myxobolus spp. of cyprinids. The species closely related to M. orissae was M. koi (FJ841887) infecting the gill lamellae of Cyprinus carpio with 96% similarity. The carp fin-infecting Thelohanellus caudatus (KC865607) from India exhibited only 78% DNA sequence similarity with M. orissae. Low level of M. orissae infection on gill caused thickening of epithelial cells surrounding the plasmodium. Under stressful conditions, it is likely that such ...

As new pathogenic strains are emerging and threatening aquaculture development, myxosporeans (Myxozoa) are receiving much attention in recent years. Myxosporean taxonomy is traditionally based on morphology of the myxospore stage. Molecular data on Indian myxosporeans are rare. In this report, the 18S rRNA gene sequence of Myxobolus cuttacki infecting gill lamellae of minor carp Labeo bata (Ham.) and its phylogenetic relationship with other myxobolids are described for the first time. The plasmodia of M. cuttacki were 0.5-0.9 mm in size and whitish with a round to oval shape. The mean mature spore size was 16.10×7.05 μm. The 18S rRNA nucleotide sequence with 1703 bp of M. cuttacki (accession number KF465682) clustered phylogenetically with other Myxobolus spp. infecting cyprinid gills with 78-90% homogeneity. The gill lamellae infecting M. catmrigalae (KC933944) and M. orissae (KF448527) of Indian major carp Cirrhinus mrigala from India, exhibited 86% and 81% homogeneity with M. cut...

In recent years, culture of Macrobrachium rosenbergii is expanding in India and West Bengal state in particular, due to its relatively fast growth rate, high market price and export demand. However, the detail study on parasitic diseases has received less attention on cultivable M. rosenbergii compared to the penaied prawns. The present parasitic survey on M. rosenbergii from coastal West Bengal state in India encountered 14 species of parasites. Among the protozoan parasites, Zoothamnium sp., Amphileptus sp., Dileptus sp., Chilodonella sp., Balladyna sp., Epistylis sp., Vorticella sp. and Gregarina sp. were recovered; of which 4 were ecto-commensals and other 4 were endo-commensals. Metazoan parasites represented by Myxobolus sp., Rhabdochona sp., Indocucullanus sp., Procamallanus sp., Cucullanus sp. and Acanthogyrus sp; of which 1 were ecto-commensals and other 5 were endo-commensals. In West Bengal state, inland culture and capture based fishery activities, mainly rural based, ar...