Phytoplankton Ankistrodesmus sp. as an alternative tool in controlling fish disease

Abstract

The ability of the freshwater phytoplankton, Ankistrodesmus sp. to inhibit the growth of the fish pathogenic bacterial, Aeromonas hydrophila and Streptococcus agalactiae was tested. The inhibitory activity of Ankistrodesmus sp. against these bacterial were observed in (1) phytoplankton culturing control medium, Bold Basal Medium (BBM) and (2) filtrate prepared from Ankistrodesmus sp. cultured in BBM. The cell densities of A. hydrophila when cultured in Ankistrodesmus sp. filtrate medium showed no significant difference (P>0.05) from those cultured in control medium. In contrast, there was inhibition activity on the growth of S. agalactiae observed in Ankistrodesmus sp. filtrate medium against those cultured in control medium. The cell density of S. agalactiae was significantly lower (P<0.05) in Ankistrodesmus sp. filtrate medium compared to the control medium started from day 4th until the 14th day. Thus, the present study concluded that Ankistrodesmus sp. can be an essential tool for inhibiting the growth of S. agalactiae