Drought conditions or at least shortage of water for fish production are common in much of Texas annually, but this year ponds are drying up like one has never seen before. Evaporation remains nearly constant from year to year, and without rainfall to replenish water in a pond, pumping will become necessary for survival of the fish population.
When water levels begin to recede, fish become progressively more stressed. If the fish are large enough, they should be harvested. Normally the fish population should be reduced to not more than 500 pounds per surface acre in the receding pond. Remove the largest fish first since they are the most susceptible to low oxygen levels. If the pond continues to recede, all fish should be removed when the water level drops below two feet.
Reduced water levels may have consequences in addition to the direct loss of fish. Warm or hot water tends to add stress to the fish, reduce oxygen levels in the water and increase the incidence of disease and parasites due to crowding of the fish into smaller areas.
Methods to alleviate the stressful conditions include:
(1) Reducing the feeding rate to not more than 1 percent of body weight daily;
(2) Adding well aerated fresh water to the tank or pond from wells or other water sources; and
(3) Increasing the oxygen levels in the water by spraying water over the pond surface.
One positive aspect of a drought is that it may give the pond owner the opportunity to perform both physical and biological renovations. Unwanted fish species can be effectively eliminated. Accumulated sediment can be removed to return the pond to its original depth. Margins and dams can be reshaped to minimize areas prone to erosion and aquatic plant growth, and emergency spillways and overflow structures can be repaired or installed.