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Pond Problems

Problems frequently arise when small ponds (less than one acre) are used for cage culture. Those problems usually center around water quality deterioration, low oxygen, ammonia or nitrite buildup, and excessive algal blooms. These problems may also occur in ponds larger than one acre but Centerare not as common. Adequate depth of the pond (6 feet or greater) is important for keeping the fish wastes away from the cage, maintaining adequate circulation through the cage, and for reducing the chance of weed encroachment around the cage. Very deep ponds are more likely to experience low dissolved oxygen problems in the summer. The characteristics of the pond’s watershed can be critical to successful cage culture. Livestock with direct access to the pond, or located in large numbers within the watershed, may cause water quality problems. Livestock wastes can overfertilize the pond leading to severe algal blooms, water quality deterioration, and eventually disaster. This is particularly true of small ponds (less than 5 acres). Livestock should be fenced out of the pond and not allowed to use the immediate pond watershed as a loafing area. As shorelines are trampled, erosion increases and ponds age prematurely. Even ponds frequented by livestock in previous years may contain large amounts of organic matter.

Highly erodible watersheds may cause turbidity/silting problems which can irritate the gills of fish and cause reduced dissolved oxygen concentrations. Watersheds where large amounts of organic matter wash into the pond can result in oxygen depletions due to rapid bacterial decomposition of the detritus.

Ponds that have a greater watershed than is needed to fill and maintain the water level can also have problems. Excessively large watersheds can cause rapid temperature changes, turnovers, and associated oxygen depletions due to water exchanges after heavy rains.

Ponds that have chronic problems such as severe weed infestations, surface scums, fish kills, stunted wild fish populations, and severe water level changes during the summer are not good candidates for cage culture. These problems must be brought under control first. It may be necessary to treat chemically for weeds or to stock grass carp (check state regulations), remove wild fish, and/or renovate (rebuild) the pond. Finally, an all-weather access road to the pond is essential to the maintenance, health, and survival of the caged fish. A day or more without access to the pond could lead to a catastrophe.

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