Effectiveness of coated controlled-released sulfate as an algicide for phytoplankton control in ponds

Abstract

Copper sulfate and diuron are the two common treatments for controlling blue-green algae, the cause off-flavor in aquaculture ponds, especially catfish ponds. Copper sulfate has been used most widely because of its lower cost. However, a number of copper sulfate applications may be required at low dose application to prevent excessive algal bloom and offflavor of the culture product. Agrium Advanced Technologies produced coated algicide products and the products were investigated the effectiveness of each product was compared with regular algicide treatments: copper sulfate and diuron. The effectiveness of a coated copper sulfate algicide designed for controlled release of copper was compared with that of regular copper sulfate, the algicide normally used in aquaculture ponds. The coated product released copper for about 10 weeks. Initially, concentrations of copper in ponds treated with the coated product were similar or greater than those in ponds receiving weekly applications of regular copper sulfate. After 3 weeks, ponds receiving regular copper sulfate had higher concentrations of copper than were observed in ponds treated with the coated copper product. Phytoplankton abundance was no greater in the ponds to which the coated product was applied than in ponds treated weekly with regular copper sulfate. The coated product was applied than in ponds treated weekly with regular copper sulfate. The coated copper product appears to be a potentially effective method for controlling phytoplankton in aquaculture ponds, and it would be easier to apply than regular copper sulfate. A coated copper product was further investigated in catfish ponds. Copper concentrations were greater in the regular copper sulfate treatment, but the coated copper sulfate treatment gave equal or possibly better phytoplankton control. Copper additions did not negatively impact hybrid catfish survival, production, or feed conversion in either the regular copper sulfate treatment or the coated copper sulfate treatment as compared to the control. Moreover, there was no difference in copper sulfate treatment as compared to the control or the two copper treatments. Flavor scores for fish did not differ among control and treatments.