Using of mustard oil cake in safe organic aquaculture through increasing pond primary productivity

Abstract

Pond fertilisation is an integral part of the organic aquaculture system. The existing practice of using manures is somewhat less acceptable due to the possibility of pathogen transmission and residual chemical exposure to the consumers. So, it is an urgent need to find out suitable alternatives. We conducted an experiment to quantitatively compare the using of cattle manure (CM) and mustard oil cake (MOC) as the organic fertiliser in earthen aquaculture pond and explored their effects on the plankton abundance and microbial water quality. The nutrient contents and microbiological loads of CM and MOC were assessed. The result of the nutrient contents analysis showed a significantly higher amount of nitrogen (5.44 ± 0.23%) and phosphorus (1.84 ± 0.05%) in MOC than CM (p ≤ 0.05). The obtained results from Mann-Whitney tests revealed that total bacterial count (TBC) (15.0 ± 0.14) and total coliform count (TCC) (13.64 ± 0.32 ln CFU/100ml), Streptococcus spp. (11.24 ± 0.08 ln CFU/100ml) and Salmonella spp. (10.62 ± 0.65 ln CFU/100ml) were significantly high at (P ≤ 0.05) in CM than MOC treated pond water. Additionally, Principal component analysis (biplot-PCA) reflects (96.6% of the total dataset) significantly higher amounts of plankton, predominantly zooplankton were found in ponds fertilised with MOC. The attained results evidenced the negative influence of CM on water and plankton abundance and recommended using MOC as a bacteriologically safe fish pond fertiliser.

Keywords

• Pond fertilisation
• Organic aquaculture
• Plankton abundance
• Water quality and nutrients