Remedial measures for oxygen depletions in ponds can be any method that adds sufficient oxygen to the pond water to prevent or minimize a fish kill. A water pump can be used to pump fresh water into the pond, or the water in the pond can be sprayed into the air and allowed to fall back into the pond. This will oxygenate the water, however, it is important that water that is sprayed is water taken from near the surface and not stagnant bottom water. Any device that agitates and aerates the water sufficiently can be of value. Do no use well water as a source for pumping fresh water into the pond, as it can be very low in oxygen.
Pesticides cause a number of fish kills in ponds throughout Alabama each year.
Convulsive, erratic swimming and lethargy are symptomatic of pesticide toxicity. If an organo-phosphate insecticide is the cause, the pectoral fins of the fish will be reversed. The pectoral fins of a healthy fish point toward the tails, but the pectoral fins of a fish poisoned by insecticide curl up and point toward the head. Generally, the small fish will be killed first and eventually all sizes of fish may die. Fish ponds should not be built in areas adjacent to crops that are likely to be treated with pesticides toxic to fish.