15 Indian J. Fish., 67(2): 15-22, 2020 DOI: 10.21077/ijf.2019.67.2.94362-03 Aspects of reproductive biology of the lesser spiny eel Macrognathus aculeatus (Bloch, 1786) from river Ganga, Uttar Pradesh, India AYSHA AZIZ FARIDI, FARAH BANO * AND M. SERAJUDDIN * Department of Biosciences, Jamia Millia Islamia, New Delhi - 110 025, India * Department of Zoology, University of Lucknow, Lucknow - 226 007, Uttar Pradesh, India e-mail: lu.fsheries@gmail.com ABSTRACT A total of 315 samples of Macrognathus aculeatus (Bloch, 1786) were collected for this study from the river Ganga at Sant Ravidas Nagar, Bhadohi, Uttar Pradesh during June 2016 to May 2017. Chi-square test (χ 2 ) confrmed that the male to female sex ratio was 1:0.93 which was not signifcantly different from hypothetical ratio of 1:1. The maximum numbers of stage IV gonads were encountered during the month of June indicated its spawning period. Mass and length ratio showed a negative allometric growth (b<3) in males (2.08102), females (2.50212) and for the sexes pooled (2.25371). The maximum and minimum values of condition factor for both the sexes of M. aculeatus were recorded during non-breeding and breeding seasons respectively. The ova diameter of ripe eggs of M. aculeatus ranged between 1.25-1.40 mm during the month of June while the single mean peak value (male =1.40 ± 0.091; female= 4.49 ± 0.059) of the gonado-somatic index pointed out that the fsh has only one breeding season during monsoon. Absolute fecundity varied from 800 to 1510, with an average value of 1247 eggs. Fecundity was found to be highly correlated with the total length (r = 0.9041), body weight (r = 0.8901), ovary length (r = 0.8721) and ovary weight (r 0.9210) which were found to be signifcant (p<0.001). Keywords: Fecundity, Ganga River, Macrognathus aculeatus, Reproduction Introduction Studies on reproductive biology of fsh is considered to be important for their management under controlled conditions and also from the evolutionary point of view (Kashyap et al., 2016). The knowledge of reproductive potential of fsh can be used in formulating the degree of rearing facilities needed and to assess the aquacultural potential. Reproductive biology studies in fsh include the assessment of sex ratio, maturity stages, duration of reproductive season, gonadosomatic index (GSI) and quantifcation of reproductive capacity (Maurua et al., 2003; De Carvalho et al., 2009; Fontoura et al., 2009; Cardoso et al., 2019). Reproductive biology is one of the most important biological aspects which is a prerequisite for evaluation of the commercial potentialities of a fsh stock and its preservation, conservation and management prospects (Jakobsen et al., 2009; Hliwa et al., 2017; Cardoso et al., 2019). GSI has been used as an indicator of reproductive activity of fsh and for determination of the breeding season (Sley et al., 2015; Almukhtar et al., 2016). The condition factor is affected by food availability, environmental conditions, population density, physical factors and the physiology of fsh including development of gonad maturity (Parrish and Mallicoate, 1995; Uthayakumar et al., 2013). The spiny eel, M. aculeatus is one of the common species of Mastacembeliformes and widely distributed in different freshwater habitats of Asian and South- east Asian countries such as Bangladesh, China, India, Indonesia, Korea, Laos, Malaysia, Nepal, Singapore, Taiwan, Thailand and Vietnam (Jayaram, 1981; Das and Kalita, 2003; Rahman et al., 2012). The spiny eels inhabit mainly in medium to large sized rivers and are abundantly distributed in low lying wetlands, freshwater streams, ponds, canals, beels and tanks. They are also available in freshwater and brackishwater within tidal infuence and are benthopelagic and potamodromous in nature (Bhuiyan, 1964; Taki, 1978; Riede, 2004). They are often found in small puddles in which mud abounds and popularly known as the ‘ditch eels’ (Hora, 1935) and are also known as the ‘lesser spiny eels’ (Munro, 1955). M. aculeatus attain upto 15 inches in length and are considered as commercially important species, palatable as an excellent food fsh with high nutritive value (Day, 1878; Sahoo et al., 2009) and also used as an aquarium species (Vidthayanon, 2002). Hossain et al. (1999) pointed out the high nutritional value of M. aculeatus as it contains 15.3% carcass protein, 22.1% muscle protein, 4.12% lipid, 78.1% moisture, 2.3% ash and 5.3 KJ g -1 energy. Prasad et al. (1983) also reported the seasonal variation in fat and water content of this fsh and the serum cholesterol level was minimal (155.0±29.5 mg ml -1 ) as recorded by Chandra (1982).