Pond Boss Forums INTRO Questions & Observations Is stunting size predictable from stocking rate?

Yes. This is true. All water is food limited. The extent of its limitations are determined by productivity ... something that varies with nutrients and community members. It can also be altered by adding food the pond doesn't grow. Anyways, if the community and nutrients (including supplemental feeds) are tightly controlled and the population of the fish controlled in number, the limit of ultimately size is very predictable and repeatable. This is the science of aquaculture.

According Swingle, the father of modern aquaculture, fish will grow until such time that the food produced is what is required to support the metabolism of the standing weight. This is why fish grow very fast in a brand new pond. The metabolic requirement of a small standing weight of fingerlings allows much of food the pond is capable of producing to be used for growth instead. By the end of the second growing season, the limit of food limited standing weight is reached and without mortality the fish can no longer grow. In other words, mortality reduces the metabolic requirement for food and so will allow the excess to be converted into growth.

All viable management methods include the management of fish numbers. For single season production, the numbers and the food are the most important factors determining the production (Harvest mortality weight - both individual weight and combined weight). Other factors including water quality (think oxygen and toxins) or survival to end of grow out also affect the results. But when water quality is good and survival is also the food and the numbers determine the results. Obviously for any fixed food amount the results are dependent on the numbers stocked.

For recreational ponds with annual carryover the numbers are not as easily controlled (due to reproduction) and so the effort is usually focused on enforcing annual mortality in terms of weight harvested. All the same this has the effect of reducing numbers and reducing metabolic requirements allowing the surviving fish to grow.