Delayed Feeding Is Practicable in Polyculture
The 45-day delayed feeding, a technique for saving on feed cost, can be practiced in polyculture, or the culture of different fish in one pond.
This was found in a demonstration project of the Bureau of Fisheries and Aquatic Resources Region II (BFAR Region II) conducted in a fish farm in Barangay Catarawan in Piat, Cagayan.
Following the recommended stocking rate of 5 fingerlings per square meter in polyculture, 6,080 size 22 tilapia (80%) and 380 common carp (5%) fingerlings were stocked into the 1,520-square meter fishpond of project-cooperator Marcial Balmores last March. Two months later, 1,140 catfish or hito (15%) fingerlings were stocked. Commercial or artificial feeds were introduced 45 days later to save on feed cost.
BFAR Region 11 Extension Chief Hermogenes Tambalque III said that this has been possible because of the symbiotic relationship of the cultured species.
“The carp, being pond bottom feeders and dwellers, help maintain water quality by eating excess feeds and other detritus. The hito, meanwhile, prevents overcrowding and feed and oxygen competition by feeding on fry or the offspring of tilapia, [which is the main culture species],” he explained.
He also pointed that the composition shouldn’t be 50% hito and 50% tilapia as hitos are voracious feeders so this might result in undersized tilapia due to predation.
Delayed feeding, on one hand, has been possible because of the presence of phytoplankton, or the natural food in the pond. These can sustain the fish during the early stage of the culture period. The green color of the water is a basis for determining the presence of phytoplankton, says Balmores.
A key to delayed feeding, according to Tambalque, is the propagation of plankton. This is done by applying chicken manure at the rate of I ton to 2 tons per hectare. Apply also 16-20-0 fertilizer at 100 kg per hectare through tea bag method (bags of inorganic fertilizer are hanged around the fishpond) to maintain water fertility.
Balmores advises to “avoid feeding at night as it might result in suffocation and mortality.” This is because dissolved oxygen level is still high. “Also, pre-empt negative effect of afternoon downpour after a hot day by immediately freshening the pond to neutralize abrupt change in water temperature.”
Overall, the delayed feeding and polyculture technology eliminates direct feed competition and ensures maximum utilization of pond resources.
On July 30, the Harvest Field Day, hito reached an average body weight of 150 grams, carp at 180 grams, and tilapia at 240 grams. Survival rate was at 85%90% and the total production based on this was 1,453 kilos.
Total feeds consumed were 47 bags. This is significantly low compared to the 10 bags per 1,000 fish feeding rate in tilapia culture. .
At retail price of P80 per kilo for carp, P85 for tilapia, and P120 for hito, projected net income is P81,087 from production cost of P47,460.
“Rarely can we reduce production cost and still have higher income and production, but this project has shown us precisely how,” says BFAR Region 11 Director Jovita Ayson. “Polyculture and delayed feeding technology can ensure sustainability in the long term through reduced organic load in the pond system.”
By Max Prudencio