A Systematic Study on Genus Mystus from Paschim Medinipur, West Bengal, India

Small indigenous freshwater fish are often an important ingredient in the diet of village people who live in the proximity of freshwater bodies. Word ‘indigenous’ means the originating in and characteristic of a particular region or country & native area. Small indigenous freshwater fish species (SIF) are defined as fishes which grow to the size of 25-30 cm in mature or adult stage of their life cycle [1]. They inhabit in rivers and tributaries, floodplains, ponds, tanks, lakes, beels, streams, lowland areas, wetlands and paddy fields. These fish can live in a harsh environmental condition and able to reproduce and grow rapidly in favourable condition. These species are not only a source of vital protein to the rural poor but also a valuable source of micro-nutrients such as calcium, zinc, iron & fatty acids [2,3]. Research has proved that the bioavailability of calcium from these small indigenous freshwater fish species is at par with that derived from milk [2]. These species also can provide a source of supplementary income to rural households. Given the local demand for small indigenous fish species of freshwater origin, the FAO [4] has also indicated the possibility of integrating such indigenous species into freshwater culture systems. Small scale aquaculture along with Indian major carps of A. mola, Puntius sophore, Osteobrama cotio, Cirrihinus reba, Labeo bata, Gudusia chapra have been reported [5-7]. In the Indian region out of 2500 species, 930 are freshwater inhabitants & 1570 are marine [8]. ZSI has recorded 2641 Pisces in 2012. A lot of works has been done in Northern region followed by southern region of India. Recent paper of Goswami et al. [9] enlisted 422 fish species from north east India, belonging to 133 genera and 38 families. Rema and Indra [10] have reported 667 species under 149 Genera of 35 families in southern region. 950 species of freshwater fishes have been found in India. If we look for the report from West Bengal, we see that a very few works has been done on freshwater fishes from the region.


Introduction
Small indigenous freshwater fish are often an important ingredient in the diet of village people who live in the proximity of freshwater bodies. Word 'indigenous' means the originating in and characteristic of a particular region or country & native area. Small indigenous freshwater fish species (SIF) are defined as fishes which grow to the size of 25-30 cm in mature or adult stage of their life cycle [1]. They inhabit in rivers and tributaries, floodplains, ponds, tanks, lakes, beels, streams, lowland areas, wetlands and paddy fields. These fish can live in a harsh environmental condition and able to reproduce and grow rapidly in favourable condition. These species are not only a source of vital protein to the rural poor but also a valuable source of micro-nutrients such as calcium, zinc, iron & fatty acids [2,3]. Research has proved that the bioavailability of calcium from these small indigenous freshwater fish species is at par with that derived from milk [2]. These species also can provide a source of supplementary income to rural households. Given the local demand for small indigenous fish species of freshwater origin, the FAO [4] has also indicated the possibility of integrating such indigenous species into freshwater culture systems. Small scale aquaculture along with Indian major carps of A. mola, Puntius sophore, Osteobrama cotio, Cirrihinus reba, Labeo bata, Gudusia chapra have been reported [5][6][7]. In the Indian region out of 2500 species, 930 are freshwater inhabitants & 1570 are marine [8]. ZSI has recorded 2641 Pisces in 2012. A lot of works has been done in Northern region followed by southern region of India. Recent paper of Goswami et al. [9] enlisted 422 fish species from north east India, belonging to 133 genera and 38 families. Rema and Indra [10] have reported 667 species under 149 Genera of 35 families in southern region. 950 species of freshwater fishes have been found in India. If we look for the report from West Bengal, we see that a very few works has been done on freshwater fishes from the region.
In West Bengal 171 freshwater fish species was reported by Sen [11]. After few years there were a wide change in number of fish species has been reported. Barman RP [12] recorded 239 freshwater species belonging to 147 genera, 49 families and 15 orders from West Bengal. 70 indigenous ornamental fish species belonging to 45 genera, 30 families and 9 orders were reported by Basu et al. [13]. All of these works are mostly based on indigenous ornamental freshwater fishes. But works on small indigenous freshwater fishes, other than ornamentals are scanty. So, the record of freshwater fish fauna of Paschim Medinipur is nil. Therefore, present work is the first attempt towards the recording of small indigenous freshwater fish fauna of Paschim Medinipur. The results presented here provide an insight to the macro-faunal diversity of the study area, and have established a baseline for future studies. Present paper is restricted only on the genus Mystus and recorded four species namely Mystus bleekeri, Mystus tengera, Mystus cavasius and Mystus vittatus from the study area.

Materials and Methods
Present study is mainly based on the specimen collected from different river, pond, bills applying different commercial fishing method throughout all the blocks of Paschim Medinipur (22° 25'N 87° 19'E) during May 2013 to November 2015. Collection of fish fauna was done at early morning and specimens were immediately preserved in 4-6% formaldehyde and were brought to laboratory in preserved condition. Then fish specimen were washed and finally preserved in 4-6% formaldehyde. Body parts of all the specimen have been dissected and studied for identification under stereoscopic binocular microscope. In some cases additional important diagnostic characters are included. The detailed synonymies have been furnished to the genera and species and also their diagnosis, distribution, taxonomic remarks and photograph of a representative species have been furnished. In addition an attempt has been made to include a comprehensive coverage of the references in reference section. For all citations of taxon author's name and year of publication has been given.

Genus Mystus Scopoli, 1777
Scopoli [14] created the genus based on the Bagrus haplepensis Valenciennes, 1840 as type species for the genus. 45 species of Genus Mystus has been found in the world and 19 species found in Indian freshwater. A brief history of the genus with special reference to Indian contribution has been given below. Pectoral fin with 7-11 rays and with a strong spine which is serrated on its inner edge. Pelvic fin has six rays. Anal fin 9-16 rays. Caudal fin forked with unequal lobes. Lateral line is complete.
Humeral spot is bold, body with five bands, three dark bands and two pale lines.
Humeral spot is faint, body with five parallel longitudinal lines.

3.
Body with two parallel stripes on each side of lateral line.
Body has a mid-lateral line.

Mystus bleekeri (Day, 1877)
Mystus bleekeri was originally described as Bagrus keletius [15] from Bengal. A brief history of the species with special reference to Indian contributions has been given below.

Mystus cavasius (Hamilton, 1822)
Mystus cavasius was originally described as Pimelodus cavasius [16] from Gangetic provinces. A brief history of the species with special reference to Indian contributions has been given below.