Growth response and survival of Heterobranchus longifilis fingerlings fed at different feeding frequencies

In an effort to utilize feed efficiently, promote growth, increase survival and reduce labour costs associated with feeding, Heterobranchus longifilis  ingerlings were placed on one of four feeding frequencies; once/day, twice/day; once every other day, and twice every other day for 56 days. Theywere fed with a commercial floating diet containing 40% crude protein level. They were reared in twelve 14 L plastic aquaria, with 3 aquaria/treatment under laboratory conditions. Each aquarium contained 10 fingerlings. The growth parameters except relative growth rate (RGR) were significantly different for fishes receiving the different treatments. Survival was not significantly different among treatments except for fingerlings fed once every other day. The study suggests that the fingerlings of Heterobrachus longifilis should be fed twice daily for higher growth performanc

Growth and survival of Clarias gariepinus (Burchell, 1822) fingerlings during single and combined commercial feeds trials

Growth and survival of Clarias gariepinus fingerlings were studied for 56 days during trials with single (blue crown or vital feed) and combination (blue crown+vital feed) of Nigeria made commercial feeds. Fingerlings were fed at 10% body weight in triplicate design. Fingerlings were collected weekly for individual total length (cm) and whole wet weight (g) measurements. At the end of the experiment (day 56), there was significant increase (P<0.05) in length (27.70±0.36 cm) and weight (166.96±5.40 g) of fingerlings fed with blue crown, followed by blue crown+vital feed (25.52±0.55 cm and 125.71±7.44 g), and vital feed (21.78±2.30 cm and 77.81±25.12 g). Similarly, for specific growth rate, significant high values (means±SEM; %/day; P<0.05) were recorded for blue crown (5.54±0.04) followed by blue crown+vital feed (5.19±0.24) then vital feed (4.03±0.66). There were no statistical differences for food conversion ratio and food conversion efficiency at the end of the trial for all treatment groups (P>0.05). In conclusion, blue crown did better than the other treatments however, it is important to note that in the combination, feeding first with blue crown enhanced the performance of the vital feed hence, single as well as the combined feeding strategy (especially with blue crown) should be recommended to farmers for enhanced growth.Keywords: Clarias, performance index, specific growth rate, feeding strateg

Evaluation of growth performance of Clarias gariepinus larvae fed artemia and aqualis starter feeds

A feeding trial, involving the use of two starter diets (artemia and aqualis) was carried out in the laboratory, to evaluate the growth performance of C. gariepinus larvae fed artemia and aqualis fish feeds. A total of 200 (48 hours old C. gariepinus larvae) of mean weight 4.8 ± 0.01mg and length 6.16 ± 0.03mm were reared for 21 days in a plastic aquarium tank of (40c m x 25 cm x 25 cm) dimension. The experiment was done for 12 hours static and 12 hours flow-through periods. The results obtained indicated no significant difference (p>0.05) in the physico-chemical parameters for all treatments in both the static and flow-through periods, however, ammonia was above the acceptable limit while nitrite and nitrate were present in low quantities, in the static water periods. These values were within the ideal range for aquaculture practice. Survival rate (%) was highest in larvae fed aqualis (58.78 ± 11.96) and low in larvae fed artemia (49.61 20.77). Artemia fed larvae recorded higher weight gain (24.64± 14.45 mg) than aqualis (15.76 ±8.83 mg). The feed in this experiment showed commendable performance in survival and growth parameters of the fish.Keywords: Artemia, aqualis, larvae, growth performance, surviva

Growth of transplanted mangrove oyster, Crassostrea gasar, (Mollusca, bivalvia) in wooden trays

From June to September 2004 we studied the survival and growth of the mangrove oyster, Crassostrea gasar transplanted from mangrove serial roots to wooden trays suspended at the intertidal area of Onne, Rivers State, Nigeria. Survival depended on stocking sizes. Oyster seed between 0.2-1.2 g, 1.6-4.8 g and 5.0- 8.0 g had survival rates between 47.0, 76.6 and 68.7% respectively. The growth rates obtained for oyster seeds for the same size range gave 0.43, 0.28 and 0.22% respectively. Analysis of variance showed that there were no significant differences (p> 0.05) in the growth of oysters between the trays. Smaller sized oyster seed had higher growth rate but poor survival rate, with oyster seeds of between 1.6 and 4.8 g (averagely 3.2 g) having the highest growth and survival. This size range therefore appears to be the optimum stocking size range to obtain a survival rate of 70% and above depending on optimum environmental conditions.Keywords: Mangove, oyster, Crassostrea gasar, seeds, Nigeria