A Preliminary Report On The Control Of Pathogenic Fungi In Earthen Culture Ponds

Copper sulfate was evaluated as a potential control for parasitic fungal infestations on largemouth bass (Micropterus salmoides) and striped bass (Morone saxatilis). Treatments were planned to reduce the incidence of free-swimming zoospores of the fungi. Largemouth bass fingerlings (15-20 cm T.L.) were stocked in 0.04 ha ponds and given multiple treatments of copper sulfate at 0.5; 1.0 or 2.0 ppm or Dimethylamine salt of 2,4-Dichlorophenoxy (acetic acid) at 2.0 ppm. Chemical treatments were made on the day before stocking and at regular' intervals thereafter for 6 treatments. Survival rates of largemouth bass treated with copper sulfate were 96, 91.7 and 100'70 at concentrations of 0,5,; 1.0 and 2.0 ppm respectively; only 10.7% of the controls survived. No significant difference of survival rate between control and 2,4-D treated fish was noted. Striped bass adults were treated with multiple copper sulfate treaments a 1.0 ppm after being captured in gill nets. All striped bass controls were lost, whereas, only 2 of 39 contacted infesetationsof fungi after treatments. Preliminary in·vitro studies showed that Formalin, Malachite Green and Potassium Permanganate are not as effective as copper sulfate.

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