Fish may die as a result. However, with proper management this problem can be avoided or corrected and where manures are available they are often the fertilizer of choice. When chemical fertilizers are added to a pond phytoplankton become more abundant. They may then be eaten directly by fish or by zooplankton and insects which are subsequently eaten by fish. A step in the food chain can be eliminated by adding manure instead of chemical fertilizer to a pond because many fish will consume manure directly.
Decomposition releases nutrients for assimilation by phytoplankton.
A simplified food chain illustrating direct and indirect consumption of fertilizer nutrients by fish follows. Simplified food chain showing pathways through which fertilizer nutrients areturned into fish flesh. Different results may be obtained under different conditions. The choice of which fertilizer to use will be influenced by local availability, cost and other factors. Read Chemical Fertilizers for Fish Ponds and Organic Fertilizers for Fish Ponds for more detailed information on fertilizer use.