Carrying capacity calculator

The answer is a range, and the pond's own water decides where in that range it falls. A pond pushed toward the top of the range takes more management to keep healthy.

Standing crop is the weight of all fish a pond holds at once, all species and sizes together. It runs from about 40 lb per acre in clear, infertile water to about 2,000 lb per acre in a fed, aerated pond run like a hatchery, and the answer for any one pond depends on what feeds the food chain. The classes here are bands from the extension tables and forum practice. The range shown is that band. It is not a measurement of your pond.

A few things narrow the range. One is water visibility, which tracks the plankton bloom (the fertilization calculator reads it by Secchi disk). Another is whether fish are fed pellets and how much (the feeding calculator). Then there is total alkalinity, since a bloom needs alkalinity above about 20 ppm to hold (the liming calculator). The last is aeration, which lets a pond carry more than the fed band without a summer kill (the pond aeration calculator). Water quality falls as fast as standing crop rises, so at the fed and intensive levels plan on aeration and daily oxygen checks.

Predators such as bass make up 10 to 15 percent of the total by weight, which is where the old rule of about 50 lb of bass per acre in a fertilized pond comes from. A newly stocked pond takes about 18 months in the South and 24 in the North to fill the range. The stocking plan calculator covers what to stock.

Sources: Mississippi State University Extension publication p1428, Managing Mississippi Ponds and Small Lakes (250 to 400 lb per acre of bluegill in a fertilized pond at 18 to 24 inch visibility). Practitioner discussion: Pond Boss forum thread Pond carrying capacity, including the ewest note that natural capacity runs 40 to 2,000 lb per acre and that water quality drops as it rises.