Corazon B. Santiago

Optimum dietary protein level for growth of bighead carp (Aristichthys nobilis) fry in a static water system

Abstract Isocalric diets (290 kcal digestible energy/100 g) with protein levels ranging from 20 to 50% in increments of 5% were fed to bighead carp fry (3.8±0.2 mg mean body weight and 9.8±0.1 mm total length) for 7 weeks. Growth in weight and length increased as the protein level of the diet increased from 20 to 30% and decreased as the protein level increased further. Although not significantly different (P>0.05) from those of fry fed the 25% or 35% protein diet, weight gain (250 mg) and increase in total length (15.7 mm) were highest for fry fed the 30% protein diet. Feed conversion ratio, protein efficiency ratio and survival rate did not clearly indicate the required protein level. The protein requirement was determined using a static-water culture system but assessment of the water quality failed to indicate an association between ammonia concentration and protein in the diet. Further research is necessary to determine why high levels of protein resulted in depressed growth.

Reproductive performance and growth of Nile tilapia (Oreochromis niloticus) broodstock fed diets containing Leucaena leucocephala leaf meal

The effects of dietary leucaena leaf meal on reproductive performance and growth of Nile tilapia were determined. In the preliminary trial, sexually mature Nile tilapia were fed with a control diet or a test diet which had leucaena leaf meal as the only protein source for 24 weeks. Fish fed with the leucaena diet lost some weight and had significantly low (P 0.05). However, growth of males fed with the 80% leucaena diet was remarkably low. Fry production was highest for those fed with the control diet and the 20% leucaena diet. Fry production decreased slightly in fish fed with the 40% leucaena diet and was significantly low (P<0.05) for those fed with the 80% leucaena diet. The low fry production was preceded by a decrease in body weight of the female fish. However, the gonadosomatic indices of the females and the males were not markedly affected by the diets. On the basis of both fry production and growth, leucaena leaf meal should not exceed 40% of the diet of Nile tilapia broodstock.

The effects of artificial diets on fry production and growth of Oreochromis niloticus breeders

Abstract Tilapia breeders were fed with pelleted supplemental diets containing 20 or 40% crude protein at a daily feeding rate of 1% of fish biomass for 24 weeks in cages and tanks. Breeders were weighed and fry were collected at 3-week intervals. The 40% protein diet consistently gave the highest fry production and growth of breeders. The 20% protein diet gave variable results; fry production and growth were comparable to those of breeders fed with the 40% protein diet in some trials but significantly low in others. Breeders without supplemental feeding invariably had the least number of fry and the lowest body weights.

Influence of feeding rate and diet form on growth and survival of Nile tilapia (Oreochromis niloticus) fry

Young Nile tilapia (12 mg mean body weight and 11 mm total length) were stocked at a density of 5 fish/l in twelve 50-l aquaria filled with 30 l of tap water. They were fed pellet crumbles containing 35% crude protein at various daily feeding rates expressed as percentages of fish biomass. Mean increases in body weight after 5 weeks were 63, 198, 232 and 228 mg for the 15, 30, 45 and 60% feeding rates, respectively, when ambient temperature ranged from 19 to 21°C. Corresponding survival rates were 53, 85, 87 and 84%. Growth and survival rates were enhanced significantly (P < 0.01) at the 30, 45 and 60% feeding rates. Two feeding trials were conducted to compare the growth and survival of fry fed pellet crumbles and an unpelleted form of the same diet. Results showed that growth and feed conversion were similar for both forms of diet. However, the survival rate of fry fed pellet crumbles was significantly higher (P < 0.01) than the survival rate of fry fed the unpelleted diet. Prior pelleting of the formulated diet for the tilapia fry given at 30% to 45% of fish biomass daily ensured high survival, fast growth and efficient feed conversion.

Growth and reproductive performance of bighead carp (Aristichthys nobilis) reared with or without feeding in floating cages

Abstract Bighead carp (10.5 months old) stocked in cages in Laguna de Bay were assigned the following feeding treatments: 1. 40% protein diet, 2. 20% protein diet, and 3. no artificial diet (control), to determine the effects of feeding on growth and reproduction. The fish were fed for 15 months. Growth was monitored for the first 9 months and fish were induced to spawn in the succeeding months. Both weight gain and increase in total length did not differ significantly ( P > 0.05) among treatments. Results of the induced spawning showed that fish fed the 40%-protein diet had the highest mean total weight of eggs/female, total number of eggs/spawning, and number of eggs/kg body weight. Fish fed the 20%-protein diet had intermediate values while the control fish had the lowest values for the same parameters. However, mean fertilization rates (54–58%) and hatching rates (61–78%) were not significantly different ( P > 0.05) among treatments. The mean number of 3-day old fry of fish fed the 20%-protein diet (48 085) was lower than that of fish fed the 40%-protein diet (86 806). The control fish gave a significantly low ( P

Effect of artificial diets on growth and survival of milkfish fry in fresh water

Abstract Wild milkfish fry (mean weight = 15 mg) were reared in fresh water for 5 weeks using four artificial dry diets, Moina , or blended water hyacinth leaves as feed. The fry fed with artificial diets attained 83–95% mean survival rates and 0.16–0.18 g mean weight gains. Those fed with Moina and blended water hyacinth leaves had much lower growth and survival. The four dry diets containing 40% crude protein appeared adequate for the fry. Substitution of up to 5% crude protein by soybean meal and/or ipil-ipil leaf meal did not affect growth, but diets containing ipil-ipil leaf meal gave slightly lower survival rates.

Milkfish (Chanos chanos) fingerling production in freshwater ponds with the use of natural and artificial feeds

Abstract Milkfish fry were reared to fingerling size in freshwater ponds. For the first experiment, fish were fed the blue-green algae Oscillatoria inoculated and grown in the ponds, Oscillatoria supplemented with a fishmeal-based formulated diet, and the formulated diet alone. Twelve 50-m 2 earthen ponds were prepared to enhance growth of the indigenous natural foods. Acclimated wild milkfish fry were stocked randomly at 90/m 2 and were fed for 6 weeks. Milkfish fed the formulated diet alone had a significantly higher ( P Oscillatoria and formulated diet (0.882±0.230 g). Growth was lowest for fish fed Oscillatoria alone. The feeding treatments in the second experiment were: combination of Spirulina powder and formulated diet, formulated diet alone, and rice bran alone. The stocking rate was equivalent to 91.5–92.5 fry/m 2 and feeding lasted for 7 weeks. All feeds promoted some growth but the milkfish fed the formulated diet alone invariably had the highest weight increment (1.504±0.167 g), followed by fish given the feed combination (0.881±0.140 g). Rice bran alone gave the lowest growth response. For both pond experiments, growth trends of the young milkfish were similar to those grown under laboratory conditions. Although survival rates were significantly different in one aquarium experiment, survival rates of milkfish in ponds did not differ significantly ( P >0.05) among treatments.