Both the number of species and the quantity of plankton in ricefields were reduced compared with levels in fish ponds. The recommended fertilizer rate and time of application also encouraged rapid plankton growth. All these species are good food for fish. In fish stomachs, organic detritus was found most frequently. Bacteria are rich in protein and are eaten by zooplankton and benthos animals as well as by fish.
Bacteria play an important role in increasing rice and fish production.
Pests and Diseases Fish diseases are rare in rice fish culture because the water is clear and the oxygen content is high. In addition, the lower stocking density and rich natural food produce strong fish that are more disease resistant. Fish pathogens are rarely seen in ricefields. Pathogenic bacteria were 1.6 times lower than in fish ponds. There were no significant differences in the number of bacteria on the fish bodies between the field and fish ponds.