Pond preparation for polyculture of fish is very important. For polyculture of fish the pond have to prepare properly before stocking minnow, so that it ensures sufficient production of natural fish feed in pond. Various steps for preparing pond are described below.
Controlling Harmful Aquatic Plants & Animals
Aquatic weeds consumes almost all the nutrition from water. As a result fishes suffers by lack of food. Along with this they also reduces the amount of oxygen in water and creates problems in regular movement of fishes. Water hyacinth, topapana, ipomoea aquatica, helenca, maloncho etc. are harmful aquatic weeds. All those weeds should remove from the root. Different types of aquatic insects are also very harmful for fish farming. So, remove them from the pond.
Eradicating Cannibalistic & Unwanted Fish
The next step of pond preparation is removing cannibalistic and unwanted fishes from pond. Shol, gozar, boal, taki etc. are cannibalistic fish and mola, dhela, chanda, pumpti etc. are unwanted fish. Cannibalistic and unwanted fish can be removed by drying the pond. If it become not possible to make the pond dry then use poison for controlling harmful and unwanted fish. For this purpose use rotenone at the rate of 16kg per acre or 400-500 phostoxin tablet per acre. But it will be better to use rotenone powder. Because it has less side effect and expires within 5-7 days.
Applying lime ensures healthy environment in pond and increases productivity. Use 100kg lime per acre in the basal level of dry pond. Fill the pond with water after 2-3 days of applying lime. If it not possible to make the pond dry then use lime in the pond at the same rate.
Applying fertilizer in the pond increases the growth and production of fish and also increases the availability of food of fish. Both organic and non-organic (chemical fertilizer) fertilizers are necessary for production of phytoplankton and zooplankton in the pond. Apply 500-700kg dung per acre after 5-7 days of applying lime. Spread the dung in every places of the pond. Apply 10-15kg urea and 5-7.5kg TSP per acre before 4-5 days of stocking minnow. Mix those chemical fertilizer with water and spread it all over the pond.