AGE, GROWTH AND HARVESTABLE SIZE OF CIRRHINUS MRIGALA (HAM.) FROM THE LAKE PICHHOLA, UDAIPUR, INDIA Bhatt Nakul Askokbhai 1* , Banukumar Sharma 2 and Tarangkumar Shah 3 1, 3 Department of Aquaculture, College of Fisheries, MPUAT, Udaipur - 313 001, India. 2 Department of Harvest and Post Harvest Technology, MPUAT, Udaipur - 313 001, India. *e-mail: nakulbhatt66@gmail.com (Accepted 25 March 2016) ABSTRACT : Age, growth and harvestable size of Cirrhinus mrigala (Ham.) from Lake Pichhola, Udaipur, India, were determined with the use of key scales. Total fiveannual rings or annuli were used to estimate selected growth parameters i.e. annual length increase (h), annual increase in weight (w), index of species average size (Q h ),index of population weight growth intensity (QC W ), specific growth rate (C I ), specific rate of weight increase (Cw), growth constant (Clt) and growth characteristic (C th ). These growth parameters indicated higher values of QC W (70.769) and Q h (12.965). The W was found to increase upto fifth year of life, while Cth increased one to five year. Similarly, the C lt and Average C lt observed during the initial phase of life i.e. upto second year were comparatively more than the last phase i.e. one to five year. On the basis of growth parameters the harvestable size of 52.00 cm and 1+ year has been calculated for Cirrhinus mrigala of Lake Pichhola, Udaipur, India. Key words : Cirrhinus mrigala, age, growth, harvestable size, lake Pichhola. INTRODUCTION Cirrhinus mrigala - an Indian major carp is commonly called ‘nain’ in Hindi and ‘mrigala’ in Bengali. It is linear fish with small head measuring over 90 cm when fully adult. Scale studies aimed at age and the growth determinations are not very common in India. Desai and Shrivastava (1990) worked on the age, growth and gear selectively of Cirrhinus mrigala (Ham.) from Rihand reservoir, Uttar Pradesh. Johal and Tondan (1983 and 1987), studied the scale in Catla catla and Cirrhinus mrigala (Jhingran, 1959). Studies on the age and growth of Cirrhinus mrigala (Ham.) from the river Ganga. Choudhary et al (1982), Jhingran (1957), Kamal (1969), Rao(1974),Ujjania (2003) restricted their studies mainlyfor back calculation of lengths. In the present study an attempt has been made to investigate the key-scale of Cirrhinus mrigala for finding information regarding size, scale rings and related dimension for calculating length at the time of annulus formation. MATERIALS AND METHODS The samples were collected from commercial catches during 2015 (using hook and gill nets). The weight and total fish lengths were recorded. Scales of this fish were found to be suitable for age and growth determination and the results obtained are in accordance with already established standards in this field. The data is based on a study of scales from 200 fish samples (mixed) collected from the Lake Pichhola, Udaipur. For this purpose randomly selected fishes were used to measure total length (cm) of each fish from the tip of the snout (mouth closed) to the extended tip of the caudal fin using a measuring tape. Body weight was measured to the nearest gram using a top loading weighing balance for all the fish samples collected. At the same time, 5-6 scales were collected from the lateral side below the first spine of the dorsal fin. Intact scales were picked up using coarse forceps. Then fish scale was dipped in with 1% KOH solutionfor 4-5 minutes to remove mucus and unwanted muscle tissue. This scale was the rinsed with tap water and preserved in tough paper envelops. After examined with the help of SCALE READER. Scale radius was measured from focus to the end of the scale whereas first annulus was measured from focus to first ring: second annulus is measurement from to second ring and so on. The age, growth and harvest size calculated using following equation. Statistical analysis Back calculation or Calculation for length and weight The back calculation technique is useful to determine fish growth in terms of length and weight each year of life prior to the data collection. The technique is especially useful if no sample were taken prior to a management activity or if only a few were sampled afterwards. The length-weight relationship (LWR) between total length (TL) and body weight (WT) can be determined J. Exp. Zool. India Vol. 19, No. 2, pp. 000-000, 2016 www.connectjournals.com/jez ISSN 0972-0030