HOW TO CORRECT LOW OXYGEN LEVEL IN FISH PONDS

Low oxygen can kill fish. The decay of excess feed and organic fertilizer consumes oxygen from pond water. Fish will die of asphyxiation if too much oxygen is consumed. Ponds receiving large applications of fertilizer and/or feed must be closely monitored to determine if oxygen levels in the pond are satisfactory for fish. Low oxygen occurs most frequently just before sunrise. Farmers should visit their ponds early in the morning to see if fish are suffering from low oxygen. Fish will come to the water surface seeking higher oxygen levels from water in contact with the atmosphere. The fish appear to be "drinking" the surface water. Almost all fish in the pond will be evenly dispersed over the pond surface and gasping for air. When scared, they will make a splash and dive for deeper water, but will quickly return to the surface. This behavior is sometimes confused with feeding. However, feeding fish will not return to the surface quickly if scared. Fish suffering from low oxygen will usually not eat. Take immediate action to remedy low oxygen using the following steps. How to correct low oxygen in ponds. 1) Add fresh water to the pond to replace water with low oxygen until fish stop gasping at the surface. More oxygen may be added to the fresh water by letting it run over a terraced structure before it enters the pond. 2) Stop fertilization and feeding for several days. Observe fish behavior closely during this time. If low oxygen has been corrected, fish will resume their normal feeding habits. When plankton abundance decreases and a submerged object is visible at a depth of 30 cm, fertilization may be resumed. 3) If low oxygen becomes a chronic problem, reduce the amount of fertilizer and/or feed placed in the pond. 4) Make use of water aerators.