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In Cameroon, wild strains of Clarias gariepinus (Burchell, 1822) are often used for artificial reproduction in hatchery facilities, but there is insufficient information on their reproductive capacity and progeny performance. The reproductive capacity of two strains of C. gariepinus from the Mezam and Mungo Rivers and the performance of their F1 larvae obtained following hybridization were assessed. Reproduction was carried out with four crosses as follows: Mezam (♂) x Mezam (♀) (T1), Mezam (♂) x Mungo (♀) (T2), Mungo (♂) x Mezam (♀) (T3) and Mungo (♂) x Mungo (♀) (T4). Thereafter, three days old larvae obtained following reproduction were subjected to a 30 day experimental trial with standard feeds. The performance of larvae obtained from T4 was not assessed since larvae obtained were too few for the experiment. Although the broodstock of the different strains did not differ significantly in size, Mezam stock had significantly (p = 0.00) bigger eggs when compared to Mungo stock. Fecundity of 52480 was recorded for Mezam stock compared to 32985 for Mungo stock. Fertilization and hatchability rates differed significantly (p < 0.05) among the crosses, with the highest (82.28 and 81.31%, respectively) in T1, followed by T3 (65.96 and 61.28%, respectively), and the least (38.61 and 2.81%, respectively) in T4. The best larval survival was recorded in T1 (37.17%) and the least in T2 (15.67%), meanwhile T3 recorded best growth after 30 days. In terms of fertilization and hatchability, T1 was more suitable for artificial reproduction, but T3 is more encouraged for aquaculture based on its reproductive capacity and larval performance.

The African River prawn Macrobrachium vollenhovenii is the largest of the local Palaemonidae prawns along the Cameroonian coast and an important target species for fisheries and aquaculture. A preliminary study on larviculture of this species was carried out at the IRAD-AQUASOL hatchery in Kribi, Cameroon. Berried females M. vollenhovenii were obtained from the Lobe and Lokoundje Rivers in the Southern Region, typical Lower Guinea rainforest streams. The larval rearing system consisted of a single recirculation system of four 65 L cylindrical plastic containers connected to a submerged biological filter container (65 L). Experiments were conducted three times in the same condition, with two batches of larvae reared separately in duplicate per experiment, at a density of 40/L, temperature 26°C, and salinity 16%. Larvae were fed from 1 day after hatching until metamorphosis to postlarvae (PL) with newly hatched Artemia nauplii, three times daily at the rate of 5 nauplii per mL water. The number of newly hat...

It has been shown that numerous fish species require n-3 polyunsaturated fatty acids (PUFA) for normal growth, while the growth-enhancing effect of dietary n-6 PUFA differ substantially among species. The present study aimed to evaluate the effect of different n-3 to n-6 ratios, underlying the effect of linoleic (LA) and linolenic (LnA) levels, on growth performance, tissue fatty acid composition and hepatic ultrastructure of Eurasian perch. Four diets were formulated using 3 different lipid sources (cod liver, safflower and linseed oils) in variable proportions in order to prepare diets with different LnA/LA ratios: 0.43; 0.03; 3.03 and 0.6 for CO, SO, LO and SLO diets, respectively. Significant results confirm the statement that an increase proportion of 18:2n-6 and 18:3n-3 in the diet of Eurasian perch, or a partial substitution of fish oil by vegetable oil, does not appear to compromise growth performance of juvenile perch. Modification of lipid utilisation by a modulation of desaturation and elongation activity in liver tissue of perch is discussed. Analyses of tissue FA profiles indicate that a minimum level of EPA and DHA has to be incorporated into the diets to comply with the EFA requirement of this species and that the overabundance of 18:2n-6 observed in SO fed fish, may cause an apparent deficiency in 18:3n-3. Consequently, the quantity of 18:2n-6 and 18:3n-3 in the SLO diet (0.64 LnA/LAratio) seems to be more suitable than in the SO diet (0.03 LnA/LA ratio) to promote ArA biosynthesis. However fish with a tissue FA profile the most similar to that of fish fed cod liver oil were fish fed the LO diet (3.03 LnA/LA ratio), suggesting the higher activity of Δ6 desaturase rather than Δ5 desaturase.