Browsing by Author "Mwanja, Mathew Tenywa"

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    Effectiveness of African Catfish Pituitary extracts, Dagin and Water flow for optimising Egg Production, Fertilisation and Hatchability in Artificial Spawning of Barbus Altianalis
    (Uganda Journal of Agricultural Sciences, 2016) Aruho, Cassius; Mwanja, Mathew Tenywa; Bugenyi, Fred; Rutaisire, Justus
    Fish inducing hormones are widely used in commercial aquaculture to facilitate continuous supply of sufficient seed required on regular basis by the farmers. The objective of this study was to optimise production of viable eggs for improved hatchability during artificial spawning in Barbus altianalis. Two experiments were conducted, namely (i) experiment I evaluated the efficiency of using catfish pituitary extracts in spawning of second generation broodstocks compared to that of Dagin and water flow. (ii) experiment II examined ripe running females facilitated to spawn by running water only. Fish treated with pituitary extracts performed much better than those treated by Dagin with respect to fertilisation rates at 80.27 ± 39.57% (U = 66.5, p < 0.001) and working fecundity at 2314.40 ± 882.04 (U = 59.5, p < 0.05). However, the difference in hatchability was not significant (p > 0.05). In experiment II, hatchability and working fecundity were significantly higher when fish were striped after 4 hours (100 degree hours at 25 oC) of running water than those striped after 10 hrs (250 degree hours) but fertilization rates were not different. The findings indicate that catfish pituitary extracts are more effective in inducing B. altianalis to spawn than those treated with Dagin. However, the observations made on ripe running females in both experiments suggest that they should not be induced with any hormone. Hence, the cost of spawning could further be reduced using running water, especially in wet seasons when the majority are ripe.
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    Evaluation of the Reproductive Performance of African Catfish (Clarias Gariepinus) Brood Stock Fed on Three Locally Manufactured Commercial Feeds
    (International Journal of Fisheries and Aquatic Studies, 2013) Ondhoro, Constantine Chobet; Mwanja, Mathew Tenywa; Nkambo, Mujibu; Kamahooro, Immaculate; Aruho, Cassius
    Brood stock management experiment was conducted at Kireka fish farm Uganda, to evaluate the fecundity and economic performance of three new local commercial feeds for African catfish brood stock development and conditioning. The fish were conditioned in earthen ponds, stocked at 0.5 kg/m3 for three months before spawning. The feeds were code named N2, B3 and N3 for Kajjansi 35%, Ugachick 35% and Tende Innovative Farm feeds respectively. Results indicated that there was no significant difference in the crude protein composition of all the test diets. Significantly lower lipid contents (2.326%) were noticed in N3. Mean number of eggs per unit brood stock weight differed significantly across all feed treatment (F = 10.179, P= 0.002), with N2 producing the highest N = 57,075± 18,922; B3= 51,477±16,266; N3= 45,375±13,399, generally improved from the baseline of 6,874±1001. Fertilization was significantly different (F=3.695E30, P=0.0001), across all diets (Mean; (N2= 78.13±8.99%; B3= 72.93±16.02%; N3= 59.95±19.96%). Hatchability differed significantly across all feed treatments (F=3.6E31, P=0.0001), compared to the baseline, Mean; (N2= 77±10.01%; B3= 67± 2.5%; N3= 58±11.15%; baseline= 45.80±5.45%). It was established that a farmer using N2 (Kajjansi) feeds would generate up to $1,114 net profit per kilogram of female brood stock spawned. While using B3 (Ugachick 35%), would generate $196 per kilogram female above total cost. N2 was the best feed overall, with the highest fecundity, percent fertilization, hatchability & net returns above total cost, followed by B3 and lastly N3. The findings of this study show that, though the profitability of a hatchery business depends on management and the germplasm, fecundity plays a crucial role in determining the net returns of the business and is greatly affected by type and quality of brood stock feeds.
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    Growth Performance and Survival of African Catfish (Clarias Gariepinus) Fed on Different Diets
    (International Journal of Fisheries and Aquatic Studies, 2017) Aruho, Cassius; Ddungu, Richard; Mwanja, Mathew Tenywa; Immaculate, Kamahooro; Nkambo, Mujibu; Ondhoro, Constantine Chobet
    Two trial experiments were conducted to assess the performance of a commercial dry feed D in combination with de-capsulated Artemia (AD), Moina (FD) and dry feed alone on African catfish larvae Clarias gariepinus for 14 days. The trials were conducted sequentially, separated by two months at the same facility to validate the consistence of the weaning effect of the feed on the growth of catfish larvae. Results showed that the final larval mean total length TL (cm) of larvae weaned using a feed combination AD (Trial 1, 1.50±0.013 1; Trial 2, 1.44±0.011), significantly performed better in both trials than that of larvae weaned on the other two diets, FD (Trial1, 1.37±0.011; Trial 2, 1.3510±0.0091) and D (Trial 1, 1.39±0.0141; Trial 2, 1.3150±0.009). There was no significant difference in the final mean total length of catfish larvae weaned on feed combinations FD and D (P>0.05). Specific growth rate (daily length % increment) ranged between 4.2% and 5.1% in all trials with the highest noted in feed combination AD. Although, weaner feed combination AD performed better than other feeds, there were no significant differences in larval survival in all the trials (P>0.05). In spite of the good performance of the combination diet (AD), results from other feed (diet) combinations were fairly good as well. Feed D (57% crude protein CP) is an imported commercial feed that has been recently introduced in the country and can be popularized as a starter feed without the need to culture tedious live feeds or use of expensive Artemia combinations.