Abstract:
Presented are methods for improving sustainability in extensive finfish pond farming and the results of their implementation on a specific farm. The results included an increase in outlet water quality, a reduction in water consumption, improved disease control, a drop in FCR, and zero use of wild-caught fish in fish feed.
First, cultivation of chlorella algae on-site and its introduction to the ponds increased DO and suppressed blue-green algae. This improved the fishes’ health, increased natural productivity, and reduced organic contamination in the discharge water. Second, a technique was developed to bypass the need for transferring fingerling from rearing ponds to grow-out ponds, reducing water discharge and intake and the fishes’ susceptibility to disease. The stocking density was then evaluated by catching a portion of the fish and using a Neutral Red dye. Finally, probiotics were added to the fishes’ diet and a potassium iodide and lactic acid mixture to the transport water as additional disease control measures.
Zero use of wild-caught fish was achieved by producing fish protein concentrate from the wastes of on-site fish processing and using it alongside yeast as major protein sources for self-produced extruded feed (pellet dissolution was minimised by using reflex feeders). This diet was complemented by the ponds’ natural productivity, which was boosted by bottom cultivation and vika-oatmeal mixture sowing prior to the pond being filled, resulting in pond bottom aeration. The plants’ remains shifted the water’s C:N ratio in favour of biofloc development and provided a substrate for periphyton.