Studies on the reproductive potential of homoplastic and heteroplastic pituitary hormones in Heterobranchus bidorsalis (Geoffroy Saint Hilaire, 1809)

Artificial induce breeding of gravid Heterobranchus bidorsalis was carried out using two hormonal materials – homoplastic and heteroplastic hormones. The study which involved 10 trials was carried out with 60 gravid female and 20 mature male. The broodfish used for the study were 18 months hatchery produced H. bidorsalis. The hormonal treatments led to the following results in terms of percentage weight loss (3.16 and 306%); fertilization rate (9522.77 ± 34813 and 8,857.93± 25557); and hatchability (9,18013± 34337 and 8,476.83 ± 34595) for homoplastic and heteroplastic hormones respectively. The mean numbers of dead eggs were 396.10± 19.15 forhomoplastic hormone injected catfish and 425.53 ± 17.09 for those injected heteroplastic hormone. Recorded deormed of larva were low (35.80 ± 1.11 and 34.27 ± 1.43) respectively for catfish injected homoplastic and heteroplastic hormones. Survival of hatchlings was high (99.61 and 9959 %) for gravid catfish inected homoplastic and heteroplastic hormones respectively. There was no significant difference (P < 005) in weight of pre and post female spawners. Although the two tested hormones investigated were effective inducers, homoplastic hormone is recommended as it recorded better results.Keywords: Homoplastic and Heteroplastic hormones, Induced spawning, Hatchability, Heterobranchus bidorsali

Induced propagation of African clariid catfish, Heterobranchus bidorsalis (Geoffrey Saint Hillarie, 1809) using synthetic and homoplastic hormones

Induced spawning of African giant catfish (Heterobranchus bidorsalis) was successfully carried out using synthetic hormone (Ovaprim) and natural hormone (homoplastic hormone-pituitary extract fromH. bidorsalis). The study which was carried out at Aquafish Farm, Ihiala, Anambra State, Nigeria, lasted 70 days (May to July). Sixty gravid females and twenty mature males of H. bidorsalis (weightrange of 310 to 550 g) were used for the study. In all, 10 trials were carried out with a control. The results showed that ovaprim performed significantly better (P < 0.01) in almost all the parametersinvestigated. The two hormonal materials gave slightly different results in terms of pre and post hormonal induced spawning mean somatic weight loss of 423.83 ± 14.19 g and 446.00 ± 13.37 g, meannumber of dead eggs of 396.10 ± 19.15 and 194.90 ± 11.00, hatchability of 9,180.13 ± 343.37 and 11,162.27 ± 362.00 hatched larvae, 35.80 ± 1.11 and 12.37 ± 1.54 deformed larvae, and 99.61 and 99.88% survival were recorded respectively for homoplastic hormone and ovaprim, respectively. Comparative cost benefit analysis showed that ovaprim which recorded better results, was also relatively cheaper.Ovaprim worth N3467.00 was used for induced breeding of H. bidorsalis with combined body weight of 13.38 kg while pituitary hormone was extracted from N 6350.00 worth of H. bidorsalis and used forinduced breeding of gravid H. bidorsalis with combined body weight of 12.72 kg. Because of its relatively cheap cost, ease of handling and better survival of hatchlings from H. bidorsalis, ovaprim ishighly recommended for hatchery users

Aspects of the reproductive biology of hatchery–reared Clarias gariepinus (Burchell 1822) in Anambra State, Nigeria II: Egg diameter

The egg diameter distribution frequency of four batches of hatchery&#8211;reared gravid Clarias gariepinus with 10 fish per batch of varying fish weights per batch, namely: 60 &#177; 0.09 g, 125 &#177; 0.11 g, 250 &#177; 0.14 g and 500 &#177; 0.12 g was studied. Eggs from paired ovaries hardened with 1% formalin in 0.6% saline solution for 3 weeks to become non-clumping were graded through a stack of eight sieves with mesh sizes: 0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.8 mm and 2.0 mm. The different batches of similar sized eggs retained at each sieve were counted. The mean egg counts of diameters of 0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm and 1.8 mm were 402.35 &#177; 70.85, 682.90 &#177; 104.40, 65.775 &#177; 10.82, 364.70 &#177; 69.26, 1829.0 &#177; 378.36, 78.0750 and 18.45 &#177; 5.64 eggs, respectively. Of the seven (7) egg diameter frequencies (0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm and 1.8 mm) monitored, the mean egg diameter frequency of 1.2 mm showed the highest egg peak and that of 1.8 mm showed the least egg peak. There were bimodal peaks occurring at 0.5 mm and 1.2 mm in the egg distribution frequency chart indicating that C. gariepinus can spawn more than once in a breeding season

Aspects of the reproductive biology of hatchery-raised Clarias gariepinus I: fecundity

The fecundity of four batch weights (10 samples each) of gravid Clarias gariepinus weighing 60 ± 0.17159 g 125 ± 0.15092 g 250 ±0.20683 g and 500 ± 0.15670 g raised from the hatchery was investigated The paired ovary of each fish was dissected out, weighed (g) and its length measured(mm). Each paired ovary was stored n a solution of 1 % formalin in 06 % saline soluton for at least 3 weeks for the solution to harden the eggs and remove egg clumping. After 3 weeks, each paired ovary was torn apart on a 2 mm mesh circular fabricated sieve over a stream of water. Theeggs passed through the 2 mm mesh sieve into a receptacle. Sub sample of the eggs from each paired ovary was taken, counted and all the eggs in each paired ovary were determined thereafterby volumetric method. The tota fecundy of 40 gravid fsh studed ranged rom 6,450 to 71,450 eggs per fsh. The mean fecundities of the 60 g125 g, 250 g and 500 g fsh were 8,501.9 ± 295.5,13,364.0 ± 1734.3, 41087.9 ± 12258.1 and 51,186.0 ± 13851.0 eggs respectvely. The relationships between fecundity and fish weight (FW) (n = 40, r = 0.8761), fsh ota lengh (TL) (n= 40, r = 0.8266), fsh ovarian weght (OW) (n = 40, r = 0.7609), fish ovaran length (OL) (n = 40, r = 0.7236), gonadosomatic index (GSI) (n = 40, r = 0.5992) and fsh condton factor (K) (n = 40, r = 0.9046) obtaned were linear and positive and the conditon factor appearedto be the best predictor of fecundity in C. gariepinus studied. The higher fecundity o C. gariepinus (range: 6,450 to 71450) obtaned from ths study when compared wth the range of 9,000 to 25,000 earlier reported from the wild stock indicates that hatchery-raised C. gariepinus is more fecund than the wild fish in the Anambra area of the sub-region. Therefore, hatchery-raised C. gariepinusappears to be better for fish breeding in fingerlngs production than the wild fish.Keywords: Fecundity, Gonadosomatic index, Condition factor, Hatchery-raised Clarias gariepinus