Strategies for describing myxozoan pathogens, dreadful fish diseases in aquaculture.

Myxozoans are obligate endoparasites, cosmopolitan in distribution with both vertebrate and invertebrate hosts. Their myxospores consist of shell valves, polar capsules with coiled polar tubules that are extrudible, and infective amoeboid germs. Myxozoan parasites are most abundant, and due to their increasing number in recent years, they can pose an emerging threat to the fish industry worldwide. Hence, the immediate need is to devise a strategy to understand and detect parasites and parasitism. They may proliferate to different organs with the advancement of infection. This all warrants the development/devising of strategies and results of integrative studies in order to identify these dreadful parasites and resolve taxonomic issues. Different methods whether classical methods including gross morphology or advanced methods such as electron microscopy (SEM, TEM, STEM), Confocal laser scanning microscopy (CLSM), histopathological studies, site preference, host and tissue specificity, a molecular approach using new markers can be clubbed for identification because these parasites are hidden and are difficult to recognize. This group was earlier classified only on the basis of myxospores morphology, but due to the high structural variability of this group advanced methods and approaches have to be implied which can minimize the problems in assigning new species.

Species diversity of the genus Thelohanellus Kudo, 1933 (Myxozoa: Bivalvulida) parasitizing fishes in Indian subcontinent.

A synopsis of 52 nominal species of the genus Thelohanellus Kudo, 1933 reported to infect freshwater fishes in India is presented. These species infect various organs such as gills, fins, scales, skin, muscles, gall bladder, kidney etc. The diagnostic features of the genus include tear-shaped myxospores with smooth shell valves and single polar capsule. The members are histozoic in their nature of parasitism infecting fresh water fishes. The present manuscript is aimed to compile the list of reported species in India along with essential information on morphometrics of vegetative stage, host, organ preference and pathogenic effects if any. Maximum number of species are recorded from state of West Bengal (25) followed by 23 in Punjab (out of which 8 were already reported from other states of India), Andhra Pradesh (7), Orissa (3), Manipur (1) and Haryana (1). Majority of the species have been recorded to infect major and minor carps (43 species) and 9 species in cat fishes. Out of 43 species infecting Indian major carps, T. batae infected the epithelial lining of gill filament of Labeo bata and also the wall of the duodenum and pectoral fin of Wallago attu in Harike Wetland (Punjab). Organ distribution of the species belonging to the genus Thelohanellus indicated that the plasmodia of 27 species were located in the gills, 14 species in the fins, 7 species in the gall bladder, 4 species in muscles and 3 species in kidney, 2 each in scale and skin on the head region and 1 species each in brain, eye, spleen, liver and wall of the duodenum. Recent studies conducted by the authors and also by few earlier studies in West Bengal have documented many species of Thelohanellus to cause serious gill haemorrhagic disease and dermal lesions. Histological studies on the gills of cultured carps in Punjab infected with members of Thelohanellus have indicated that these parasites cause 15-20 % damage to respiratory surface leading to localized loss of function.

First record of myxozoan parasites from fresh water fishes of Jammu and Kashmir and their pathogenecity.

The present study was aimed to isolate myxozoan parasites infecting the native carp Schizothorax esocinus (Heckel) and pond reared carp Labeo rohita (Ham.) collected from fresh water ecosystems of Jammu and Kashmir from July 2013 to June 2014. Various organs such as eyes, gills, scales, fins, intestines, visceral organs and pericardial cavity of as many as 100 live specimens were examined. Results revealed that 14% of the examined L. rohita were infected with Myxobolus rocatlae (Ham.) and 6% of S. esocinus (Heckel) were infected with M. kashmirensis sp. nov. Clinical signs revealed mucous laden gills while the parasitological observation under stereozoom binocular microscope revealed multiple minute plasmodia on the gills. On rupturing these plasmodia with sharp needle 100-500 myxospores were liberated. The identification to species level was done on the basis of morphological and morphometric attributes of the myxospores. This is the first record of myxozoan parasites in fishes from the state of Jammu and Kashmir, India. Histological observations of infected gills revealed plasmodia of two types (LV4 intralamellar vascular type) in M. rocatlae and (LV3 intralamellar vascular type) in M. kasmirensis causing necrosis, hyperplasia, hypertrophy and vacuolization of the epithelial and vascular endothelium.

Myxobolus chushi n. sp. (Myxozoa:Myxosporea) parasitizing Schizothorax niger (Heckel), a native cyprinid fish from Wullar Lake in Kashmir Himalayas.

In the study, a new species, Myxobolus chushi n. sp. infecting gills of wild specimens of Schizothorax niger (Heckel) inhabiting Wullar Lake in Kashmir Himalayas, (J&K) India has been described based on morphology of the myxospore and using partial 18S rDNA sequencing. Pathological changes in the gills have been studied with the help of histological sections stained with Luna's method. Twenty fish specimens were examined, out of which four had oval, white plasmodia in gills measuring 2.0×0.5mm. The myxospores were spherical to ovoidal in shape with slightly attenuated posterior end, measuring 11.17±0.23 (10.60-11.40)µm in length and 9.14±0.06 (8.80-9.20)µm in width, having a prominent pore at the anterior end. The polar capsules were pyriform in shape, measuring 4.25±0.15 (4.00-4.40)µm in length and 2.38±0.27 (2.00-2.65)µm in width having polar filaments forming coils up to 5 in number. Parietal folds 9 in number present on the posterior part of the shell. The intensity of infection was recorded to be moderate as indicated by gill plasmodial index (GPI=2). The plasmodium was located in the vascular network occupying whole of the gill lamella therefore typed as intralamellar vascular type, LV3. Analysis of 18S small subunit (SSU) rDNA sequence of the isolate demonstrated 90% homogeneity with M. sp. KLT-2014 infecting scales of Labeo rohita from Myanmar and 89% with M. dermiscalis infecting scales of Labeo rohita from India.

Endoparasites of some economically important food fishes of River Jhelum, Kashmir (India).

During the present study endo-parasitic fauna of fish at different sites of River Jhelum were analysed. Four different species of endoparasites were recovered from Schizothorax species which include Adenoscolex kashmirensis Mehra, 1930, Bothriocephalus acheilognathi Yamaguti, 1934, Echinorhynchus sp., Pomphorhynchus kashmirensis Kaw, 1941, belong to Phylum Platyhelminths and Phylum Acanthocephala. Prevalence and generation time were inversely proportional to each other. Prevalence and mean abundance were highest at Qamarwari. Diversity was more at Tengpora. Cestodes including Adenoscolex kashmirensis and Bothriocephalus acheilognathi were more dominant than Pomphorhynchus kashmirensis and Echinorhynchus sp.

Population analysis of the genera buildup on some commercially important vegetable crops grown in Kashmir Valley.

In order to list the genera buildup on Brassica oleracea (Cauliflower), Capsicum frustscens (Chillies), Spinacia oleracea (Spinach) and Phaseolus vulgaris (Farash bean) a general survey was carried in the summer season of 2013. On examining the soil samples as well as root samples of Cauliflower Boleodorus, Psilenchus, Helicotylenchus, Merlinius, Aglenchus and Filenchus were encountered with their absolute density of 18, 31, 34.5, 35, 35 and 31.5 %. On Chillies, Tylenchus, Helicotylenchus, Psilenchus, Pratylenchus and Hirschmaniella with their absolute frequency of 86, 96.6, 100, 100 and 96.6 % respectively were collected. Among these five genera recorded on Chillies the Relative prominence value of 16 % is lowest for Psilenchus and 26.7 % for Helicotylenchus. Merlinius, Psilenchus, Aglenchus, and Boleodorus were encountered on examining the soil and root samples of Spinach during the period of study. Boleodorus was met with the highest percentage of frequency of 90 % as well as highest proportion of absolute density of 37 % and lowest value of 24 % in case of Merlinius and Psilenchus. Soil samples as well as root samples of Farash bean, Aglenchus, Tylenchus, Hirschmaniella, Helicotylenchus and Psilenchus were encountered with their absolute density of 27, 19.5, 33, 33 and 35.4 %. The absolute frequency of 100 % was found in Tylenchus with the lowest frequency of 70 % in Helicotylenchus. Among the genera recorded on Farash bean relative prominence value happened to be highest in Hirschmaniella with the value as 23.6 % and lowest on Tylenchus with the value of 14.2 %.

First record of protozoan parasites in cyprinid fish, Schizothorax niger Heckel, 1838 from Dal lake in Kashmir Himalayas with study on their pathogenesis.

Trichodina heterodentata Duncan, 1977 and Ichthyophthirius multifiliis Fouquet, 1876 obtained from gills during a parasitological survey conducted for the protozoan parasitic fauna of Schizothorax niger a snow trout in Dal Lake, Kashmir, India during the period October 2013 and March 2015. Thirty out of 180 fish were found infected with protozoan parasites. During the study of their pathogenecity the most common deteriorating signs observed in gill tissue were necrosis, hypertrophy, hyperplasia and fusion of secondary lamellae. Prevalence of infection was found to be 16.66%. This is the first record of the protozoan fauna of the schizothoracines from Kashmir valley, India.

Myxobolus nanokiensis sp. nov. (Myxozoa: Bivalvulidae), a new pathogenic myxosporean parasite causing haemorrhagic gill disease in cultured Indian major carp fish, Labeo rohita (Hamilton 1822) in Punjab, India.

The plasmodia of Myxobolus nanokiensis sp. nov. were found infecting gills of Labeo rohita (Hamilton 1822) The infection rate was found to be 36.67 % (30 fishes were examined and 11 fishes were infected) in the Nanoki pond in Patiala district Punjab. Numerous minute plasmodia each filled with 150-200 spores were detected. Smear of scrapped blood-tinged mucous from gills exhibited millions of spores. Histological sections also indicated numerous plasmodia measuring 38.33-40.33 µm in diameter in the blood vessels of gill filaments. Spores of M. nanokiensis sp. nov. were elongate pyriform in shape and morphologically unique in having sharply pointed beak-like anterior end. Spores measured 9.28 µm × 5.71 µm in size. Polar capsules were equal, pyriform, 5.71 × 2.73 µm in size, each having polar filament with 7-9 coils. The present species has been proposed as new on the basis of its peculiar shape and morphometrics. This is the first report of any myxobolid infection in the farmland fishes in Punjab (India). The plasmodia in the gill filaments were of intralamellar vascular type (LV) and were present within the entire length of the filament. These plasmodia caused hemorrhage, necrosis of the blood vessels and cellular infiltration.