75 Indian J. Fish., 63(4): 75-81, 2016 DOI: 10.21077/ijf.2016.63.4.57190-12 Captive broodstock development of common carp Cyprinus carpio Linnaeus, 1758: infuence of age on spermatogenesis and fertilisation parameters C. JUDITH BETSY 1 , J. STEPHEN SAMPATH KUMAR 2 , K. THILAK PON JAWAHAR 3 , S. ATHITHAN 1 , B. AHILAN 1 AND K. KARAL MARX 1 1 Department of Inland Aquaculture, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Thoothukudi - 628 001, Tamil Nadu, India 2 Centre for Sustainable Aquaculture, Tamil Nadu Fisheries University, Nagapattinam - 611 001, Tamil Nadu, India 3 Department of Animal Genetics and Breeding, Veterinary College and Research Institute, Tamil Nadu Animal sciences and Veterinary University, Tirunelveli - 627 001, Tamil Nadu, India e-mail: betsyjudith@gmail.com ABSTRACT Knowledge on the quality of male and female gametes which may affect fertilisation success and larval survival is necessary to enhance fsh production to meet global demand. Gamete quality is affected by factors like sex ratio, stocking density, age, size, nutrition and feeding regime. In the present study, the spermatological and fertilisation parameters as infuenced by the age of brooders of Cyprinus carpio Linnaeus 1758 developed under captive condition from a single population were studied with special reference to dilution ratios. Milt was collected from 6, 12 and 18 months old brooders of C. carpio and diluted at three ratios viz., 1:40, 1:80 and 1:120 using freshwater fsh saline. Sperm density, spermatocrit value, seminal plasma composition, motility duration, fecundity, fertilisation and hatching rates were studied for brooders of all age groups. The results showed that milt from 12 months old brooder produced good quality milt in terms of motility duration (69.66±4.72 sec), fertilisation rate (91.3±3.05%) and hatching rate (76.5±2.64%) at 1:40 dilution ratio. Keywords: Age, Common carp, Dilution ratio, Fertilisation, Spermatogenesis Introduction Common carp Cyprinus carpio Linnaeus 1758 is a highly preferred food fsh and cultured worldwide. During 2013, the production of C. carpio was 4 million t (FAO, 2015) and ranked third globally.Common carp spawns throughout the year in tropical areas, with peaks in January-March and July-August. In wild condition, carps are partial spawners whereas domesticated carps release all their mature eggs within a few hours. The quality of male and female gametes may affect fertilisation success and larval survival (Rurangwa et al., 2004). Generally, the sperm motility, sperm concentration, egg diameter, fertilisation rate and hatching rate are used as indices of gamete quality (Aliniya et al., 2013). Motility parameters are used to evaluate the quality of the spermatozoa (Billard et al., 1995). Spermatozoa motility, milt volume and sperm concentration are considered as good indicators of milt quality (Cabrita et al., 2001; Tekin et al., 2003). The quality of fsh eggs is generally determined by their fertilisation rate and hatchling survival. Good quality eggs exhibit low mortality levels at fertilisation, hatching and frst feeding (Brooks et al., 1997). Poor quality eggs have delayed cortical reaction and slow rise in osmolarity after fertilisation (Kjorsvik and Lonning, 1983). The age of broodstock infuences the quality of the gametes produced. Although there are no strong evidences or reports on the changes in the quantity of spermatozoa at different age, many researchers reported decreased relative fecundity in female fshes as age advances (Siraj et al., 1983; Springate et al., 1984). The age of broodstock also affects the success of sperm storage. According to Tempero et al. (2006), age at maturity in common carp is related to latitude and sex. They also stated that males mature before females and fsh mature earlier at low latitudes compared to higher latitudes. Parameswaran et al. (1972) reported that in pond culture in India, males mature at 6 months of age and females at 8 months. Considerable variations occur in the spermatological quality of milt collected from one individual at different times of the same season. Factors such as age, health status, physiological condition and maturity stage are known to play a role in the milt quality and reproductive