When ponds are built, the top soil is alkaline and fertile. However this soil is removed and the soil left to build dykes is less alkaline and in some cases very acidic. Ponds built in areas which have acid soils and soft water may not always perform well for fish production. Such ponds may benefit from liming if the water has a total alkalinity of less than 20 mg/l.

Why Lime your fishpond?

If a fish farmer applies fertilizer and the pond does not bloom ( i.e. green water color due to the growth of phyto and zooplankton) within seven days the problem could be that the pond water is low in alkalinity (is acidic) and thus requires liming. Clay soils are often acidic and because ponds are commonly constructed on these soils, they have low alkalinity and hardness and so require liming. If your pond is in a dry area, that is, one with little rainfall, you may not need to apply lime to it because the pH is already high.

Note you can buy simple cheap test papers or slightly more expensive water test kits which will tell you how alkali or acid (measured as pH - 1 very acid, 12-14 very alkali) your soil and also your water is.

The water test kits will also allow you to measure other key water quality parameters.  Such water quality kits are well worth buying for fish farmers. Visit our directory and browse through the various providers