Functions of a stream unit on the growth of phytoplankton, zooplankton and fish fry in a new culture tank system

Abstract

The functions of a stream unit in a new culture tank system, which was composed of the stream unit and a conventional tank, were evaluated by cultivation of phytoplankton (freshwater Chlorella sp.), Zooplankton ( Moina micrura) and fish fry ( Puntius gonionotus). Ratios of the growth rates of phytoplankton and zooplankton in the new tank system, to the control tank were 1·2:1 and 1·1:1 on average, respectively, and ratios of total weight of fish growth were 1·1:1. On the basis of the results and several water quality parameters (DO, PO 4P content and pH), the follwing functions were considered: 1. (1) Enhancement of the growth of algae, water weeds, and bacteria; (a) production of food materials for zooplankton and fish, (b) oxygen supply, (c) pH increase, (d) absorption of nutrients, (e) acceleration of decomposition of biodeposits. 2. (2) Accumulation of biodeposits.