Potential of Macrophytes as Alternative Fish Feed Ingredients for Sustainable Aquaculture

Freshwater macrophytes are gaining importance as nutritious ingredients for fish feed formulation. In this study, the nutritional and anti-nutritional contents of the valuable macrophytes were evaluated. Freshwater macrophytes including Lemna minor, Spirodela polyrhiza, Wolffia globosa, Pistia stratiotes and Ipomoea aquatica were cultured with organic manures including cattle dung, poultry droppings and mustard oil-cake in 1:1:1 combination @ 1.052 kg/m3. The temperature and light intensity ranged 20-28ºC and 4346-5352 lux, respectively during the culture period. The proximate composition study showed that significantly (P<0.05) higher crude protein content present in L. minor (35.94 ± 0.05%) and S. polyrhiza (35.21 ± 0.31) among other cultured macrophytes. Significantly (P<0.05) higher crude lipid (8.13 ± 0.06%) with higher calorific value (3.79 ± 0.01 Cal/g) found in L. minor only compared to others. Significantly (P<0.05) higher ash content (21.69 ± 0.23) was present in P. stratiotes. The anti-nutritional analysis study showed that phytic acid content significantly (P<0.05) higher in I. aquatica (2.10 ± 0.02%) followed by P. stratiotes (1.85 ± 0.01%). P. stratiotes had significantly (P<0.05) higher tannin (0.96 ± 0.02%) and saponin (1.59 ± 0.04%) content among other cultured macrophytes. Saponin content was significantly (P<0.05) lower in W. globosa compared to others. Significantly (P<0.05) lower tannin content was found in duckweeds L. minor and W. globosa. These results indicate that some freshwater macrophytes have favorable nutritional properties and may be used to formulate sustainable fish feeds that reduced the costly fishmeal in aquaculture.