How to stock farm ponds during hot summer months

Iowa State University Extension
Mike Miller, vice president of the Millers River Trout Unlimited chapter, stocks the pond with various species of trout.

AMES, Iowa – Due to recent high temperatures and dry conditions, stocking farm ponds can be difficult to do this time of the year. However, several measures can be taken to increase your success.

Last year was a popular year for the aquaculture industry. While COVID-19 had negative effects on many economies, there was actually an increase in fish sells for ponds during the pandemic. Additionally, due to drought in the fall of 2020, there have been many complete and incomplete fish kills. Therefore, many pond owners are looking to replenish their farm ponds this year. 

The first step in restocking a farm pond is taking inventory, according to Joe Morris, professor in natural resource ecology and management, and extension fisheries/aquaculture specialist at Iowa State University. Producers can take farm pond inventory in a few different ways, but the main objective is to replenish a farm pond with a sustainable ecosystem of large fish predators and small fish prey.

Additionally, look for evidence of reproduction. To see what a pond is populated with, a pond owner could try to catch various fish in different pond areas; use a small minnow seine or set fish traps at different pond locations.

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.

For more information, Morris can be reached at (515)294-4622 or jemorris@iastate.edu.