The effect of fresh duckweed (Lemna minor L.) and fresh taro (Colocasia esculenta) leaves on the growing Tilapia (Oreochromis niloticus) and Silver Carp (Hypophthalmichthys molitrix) fish

Chhay Ty¹, Sen Sorphea¹, Kong Saroeun¹, T R Preston²

¹Center for Livestock and Agriculture Development (CelAgrid). Prah Theat village, Sankat Rolous, Khan Dangkor.  PO Box 2423 Phnom Penh 3, Cambodia
chhayty@celagrid.org

² Fundación para la Producción Agropecuaria Tropical Sostenible Capitulo Colombia,

Abstract

The main of the experiment was studied effect of fresh duckweed (Lemna minor L.) and fresh taro (Colocasia esculenta) leaves on the growth performance of Tilapia (Oreochromis niloticus) and Silver Carp (Hypophthalmichthys molitrix) fish in 5 m² each pond (2.5m * 2m) with 1 m depth. Total of 192 tilapia and 48 silver carp which fish stocking density is 4 fish/m². The experiment design was Completely Randomized Design (CRD) with 2*2 factorial arrangements of 4 treatments and three replications within each treatment, the first factor was fish species {(Tilapia alone and mixture species (Tilapia 60% and Silver carp 40%)} and second factor was protein sources from duckweed or duckweed mix with fresh taro leaves (60:40% in DM basis). All of fish ponds were fertilized the same amounts of biodigester effluent from concrete biodigester loaded with pig manure in the rate of 140 kg of N/ha/year and applied two times a week, while protein sources were offered at rate of 5% of fish weight. The experiment was conducted for 100 days. The daily weight gain (DWG) was better for single Tilapia (TL) treatment and Tilapia mixing with Silver Carp (SC) but lowest on SC (P=0.007), however, both fish species was effect on DWG when fed duckweed (DW) alone compared with mixture duckweed and fresh taro leaves (DW-FTL) (P=0.01). The daily length gain (DLG) were not effect on fish species (P>0.05) but protein sources was high on DW treatment compared with DW-FTL (P=0.011). The ratio of weight and length gain were not different on single TL (3.56g/cm) treatment and TL (3.43g/cm) mixing with SC but lowest on SC (2.70g/cm). However, the fish survivals were not effect on fish species and protein sources. The fish yield was highest on single TL (1737.6kg/ha) but lowest on SC (545.7kg/ha). The protein sources was highest on DW (1220.2kg/ha) treatment rather than mixture (DW-FTL) (959.4kg/ha). Water parameter were not different in all water parameter (P>0.05). It was conclude that Tilapia are better than Silver Carp in term of growing and yield, however, both fish species are better growth rate and yield when fed duckweed alone compare with mixture with fresh taro leaves.

Key words: Tilapia, Silver Carp, duckweed, fresh taro leaves, biodigester effluent, weight gain, length gain, survival, yield