With incomplete fish kills, it is most likely that the pond will need larger fish that can survive predation. Morris wrote an article about fish species that will fit specific farm ponds on the ISU Extension and Outreach Natural Resource Stewardship website. Additional publications about fish stocking can also be found, including “Building Quality Ponds – Managing Iowa Fisheries.”
Once there is an understanding of what kind and number of fish need to be stocked, some communication with the fish vendor is beneficial. Within this communication, the fish buyer should know how the fish ordered are usually transferred. Knowing the conditions the fish will be in before transfer helps the producer acclimate the fish to the new settings of the pond and increase the chances of fish survival.
"When you buy your fish, the biggest thing you need to do is acclimate the fish to the water,” said Morris. “Through taking your time and transferring pond water slowly to the container with the fish, the fish will be conditioned to the pond’s environmental conditions."
This summer's drought and warmer weather have caused an increase in farm pond nutrients and water temperature. Both of these factors will not be present in the water that the fish are kept in before the pond.
Therefore, to ensure that the fish do not go into shock when they enter the pond water, one can slowly introduce small amounts of pond water to the fishes transfer water. This can be done by bringing pond water with you to purchase the fish or by slowly transferring water back and forth while on the edge of your pond. Just remember that one gallon of water is over eight pounds, so be careful not to overload your equipment.
Another factor that can help your fish survive transfer is picking a strategic date and time. The heat and the bright sun are both harmful to fish, so choosing an early morning on an overcast day to stock your pond during the summer will increase your chances of success.
Source : iastate.edu