Development of a duckweed-fed carp polyculture system in Bangladesh

In an effort to develop a duckweed-based carp polyculture system, the effects of duckweed (Lemna sp.) application on pond ecology and fish production, and optimization of phytophagus Thai silver barb (Barbodes gonionotus) for this system were investigated in two separate experiments conducted at Mymensingh, Bangladesh. Duckweed had significant positive effects on growth rates of exotic Thai silver barb and common carp (Cyprinus carpio) and indigenous catla (Catla catla), whereas, indigenous rohu (Labeo rohita) was not affected by duckweed. A stocking density of Thai silver barb at the rate of 6000 fingerlings ha(-1) with 3300 rohu, 3300 catla and 3400 common carp fingerlings ha(-1) was found appropriate species mix for duckweed-fed polyculture system. This combination resulted in a net fish production of 2020 kg ha(-1) during a 4-month culture period. (C) 2003 Elsevier Science B.V. All rights reserved.