The potential algaecide flumioxazin has little effect on growth, survival and feed conversion of the bluegill sunfish Lepomis macrochirus.
An effective and benign approach to mitigating fish-killing Prymnesium parvum blooms in small impoundments has yet to be identified. The aquatic herbicide flumioxazin (Clipper®, Valent Corp., Walnut Creek, CA), however, shows promise as it suppresses P. parvum while having little effect on other plankton. Its influence on fish has yet to be evaluated. Here, we investigated potential effects of flumioxazin on growth, survival and feed conversion ratio of a non-target organism, bluegill sunfish (Lepomis macrochirus) in a laboratory experiment. We exposed fish to several herbicide concentrations that spanned the manufacturer's recommended dosage (0, 25, 50, 100, 200 and 400 µg L-1). The duration of the experiment was six weeks with weekly re-application of flumioxazin to specified tanks. No significant differences were found in average fish weight gain (p=0.76), percent survival of fish (p=0.83) or the feed conversion ratio (p=0.89). These findings provide further evidence that flumioxazin application may be an effective and benign approach to P. parvum mitigation.