Effects of Different Physiological Saline Concentrations on the Reproductive Performance of Clarias gariepinus (Burchell, 1822)

Abstract

This study aimed to investigate the effect of different concentrations of physiological saline (0, 3, 6 and 9 g/l as control) on the reproductive performance of Clarias gariepinus within 7 days of induced breeding. At the end of the experiment, there were significant increases (ANOVA, p>0.05) in fertilization, hatching and survival rate with an increase in physiological saline concentration up to 6 g/l. Values were (mean ± standard deviation, SD, %) 94.3 ± 1.1, 88.8 ± 3.0 and 78.7 ± 2.3 for fertilization, hatching and survival rate respectively. The physico-chemical parameters were measured and values were within the ideal range for C. gariepinus production. Overall, the results indicated that milt prepared in 6 g/l physiological saline concentration is the most ideal for fertilization, hatching and survival of C. gariepinus larvae 5 Journal of FisheriesSciences.com Journal abbreviation: J FisheriesSciences.com Amachree et al., 12(4): 004-008 (2018) of the genitals (Ayinla, 1994). The gravid female brood stocks of C. gariepinus were selected based on the swollen, reddish genital opening while male were based on reddish and pointed genital papillae. Brood stocks were transported in plastic troughs from the farms to the Fisheries laboratory of the Rivers State University. Brood stocks were acclimated and conditioned in separate tanks for one week and were fed with 40% crude protein commercial pelleted feed at 3% body weight twice daily at 9.00 and 18.00 hours. Feeding was suspended 24 hours prior to inducement. Administration of hormone Female brood stock of C. gariepinus was injected intramuscularly into the dorsal muscle above the lateral line with ovaprim at 0.5 ml/kg fish and kept in a trough with minimal water for conditioning (Achionye-Nzeh, 2012). Preparation of physiological saline solution Sodium chloride were weighed 0, 3, 6 and 9 g using a sensitive weighing balance and dissolved in one liter of distilled water to give final concentrations of 0, 3, 6 and 9 g/l respectively. The solutions were stirred vigorously for homogenous mixture. Collection and preparation of milt All the male C. gariepinus brood stock was sacrificed and testes removed. Milt were collected from individual fish by cutting the testes into smaller pieces. Milt were squeezed and washed into already prepared concentrations (0, 3, 6 and 9 g/l) of physiological saline to keep the sperm dormant but alive. Thereafter, milt was sieved to remove dead tissues (Achionye-Nzeh, 2012). Experimental design The complete randomized design was used for this experiment. Female brood fish were stripped of their eggs into four individual plastic basins. Thereafter, the milt already prepared in the different concentrations (0, 3, 6 and 9 g/l) of physiological saline concentration was added for fertilization. Fertilized eggs for each treatment were randomly distributed in triplicate design (i.e., 3 troughs/ treatment) into a total of 12 plastic troughs for incubation and subsequent rising of hatchling for 1 week (7 days). Feeding The larvae in each of the experimental troughs were fed on commercial diet (Coppens) at 3% of their body weight (Viveen, 1985). Feeding was done twice daily to enhance optimum growth (Davies, 2006). The daily ration was divided into two equal parts. One part was fed at 9 hours and the other part of 18 hours. Feed was dispensed evenly on the water surface in each tank to allow equal opportunity for feeding. Measurement of reproductive performance Calculation of number of eggs released: The number of eggs released in each experimental trough was determined (Viveen et al., 1985; Davies et al., 2006; Ndimele et al., 2011; Owodeinde, 1822). Briefly, the weight of the brood stock after stripping (W b , grams) was subtracted from the weight of the brood stock before