Common Problems With Farm Ponds

Introduction   |    Fish Kills   |   Muddy Water   |   Leaking Ponds   |   Wildlife

Common Causes

Occasionally, a fish kill occurs in farm ponds because of water quality problems such as oxygen depletion, infectious disease, swarming fire ants (in the spring), or misused agricultural chemicals (pesticides). In some cases, the losses may be enough to affect the balance of the fish population. Therefore, get professional help to evaluate the fish population balance following a fish kill. In many cases, a phone call will provide enough information.

Oxygen Depletions

This is probably the biggest cause of fish kills in farm ponds. Oxygen depletions usually occur July through September during the period of highest water temperature. Die-offs caused by low dissolved oxygen levels result from natural biological processes, and there are rarely any effective preventive measures. One common cause of oxygen depletion is die-off of microscopic algae during several days of cloudy weather. Decay of these microscopic algae uses up the dissolved oxygen the fish require for respiration.

Another phenomenon, often called "pond turnover," can occur after heavy cold rains in late summer or in early fall when temperatures drop suddenly. This is actually a mixing of warm surface waters with cooler bottom waters, more properly termed "destratification," and often results in an oxygen depletion. An early symptom of a low dissolved oxygen level is when fish are at the surface of the pond at sunrise. Fish appear to be "gasping for air." Adult fish die first, and intermediate fish follow if the low oxygen level continues for many days. Usually, some fingerling fish will survive, but there is a tendency toward overcrowding bream afterward. Stocking yearling size largemouth bass in the fall may be advisable if there are no undesirable species (such as crappie) in the pond.

Fire Ants

During warm spring rains, fire ants are often washed into ponds, and small and intermediate sized bream may die from eating these insects. Bass are rarely affected. This condition generally does not have a detrimental effect on the population balance.

Infectious Diseases and Parasites

Bream and bass generally do not have significant problems with infectious diseases in well-balanced ponds, although an occasional sore may be evident on individual fish during spawning season or following an injury. These external sores do not pose any health hazard to humans. As previously suggested, never throw bream back, and remove bass with sores from the population. Occasionally, bass and bream are caught that contain small white or yellowish grubs imbedded in the flesh. These grubs, although not pleasant to look at, pose no threat to humans. The affected area can be trimmed away, and the remainder of the fish is safe to eat.

Infectious diseases and parasites of channel catfish are common problems in catfish ponds. Factors contributing to this in recreational ponds include overstocking, inconsistent feeding, and poor water quality. Disease and parasite problems of catfish rarely occur when low stocking densities (100-150 per acre) are used. Stress from handling may cause die-offs of fish within 2 weeks of stocking new or established ponds. If you choose to stock catfish at rates higher than recommended here (100-150 per acre), then you should plan ahead to cope with problems that may occur.

Determining the Cause of a Fish Kill

f you experience a fish kill and suspect that infectious disease or parasites may be the cause, you can send fish samples to the Mississippi State University College of Veterinary Medicine (for recreational ponds) or the Thad Cochran National Warmwater Aquaculture Center (for commercial aquaculture ponds) for analysis. Please contact them beforehand at 662-325-3432 (CVM) or 662-686-3302 (TCNWAC) to make arrangements for sending or transporting fish.

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