Submitted to: North American Journal of Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/19/2003
Publication Date: 4/1/2004
Citation: Schrader, K., Foran, C.M., Holmes, B.D., Schlenk, D.K., Nanayakkara, N., Schaneberg, B.T. 2004. Toxicological evaluation of two anthraquionone-based cyanobacteriacides to channel catfish. North American Journal of Aquaculture. 2004. V. 66. P. 119-124. Interpretive Summary: A natural product derivative that is effective for controlling musty-odor producing blue-green algae in catfish ponds was tested to determine its effect on channel catfish. The concentrations that were harmful to catfish were determined to be well below the levels required to control blue-green algae. In addition, the natural compound was determined to be non-mutagenic.
Technical Abstract: The use of biocides to control blooms of cyanobacteria (blue-green algae) is important for the aquaculture industry to limit the off-flavor effects of chemicals produced by these organisms. However, the consequences of exposure on fish health will determine the effective use of biocide treatment. A biocide, an anthraquinone derivative, specific to cyanobacteria was evaluated for the following: 1) mutagenicity, and 2) acute toxicity and histopathology using channel catfish fingerlings, Ictalurus punctatus. Mutagenicity of the natural product derivative was evaluated using Salmonella typhimurium and a plate-incorporation assay. Results from the assay indicate that the natural product derivative is non-mutagenic. Acute toxicity was determined through measurement of mortality following 96 h of aqueous exposure (96-h LC50). Following a one-week acclimation, a group of ten catfish fingerlings were exposed at each of six different concentrations ranging from 0.01 mg/L to 20 mg/L. A group of ten unexposed fingerlings served as the control. The 96-h LC50 for this compound was determined to be 1.95 0.69 mg/L. Among catfish from the sub-lethal doses, no differences were detected in body size (weight and length), gill and liver weight, and percent hematocrit. The gill and liver tissues from each catfish were fixed and then sectioned to identify histological changes that could be related to the mechanism of toxicity. Histological analysis revealed abnormalities in the gills of catfish treated with sub-lethal concentrations (1 mg/L and less). These abnormalities at sub-lethal concentrations could not be directly linked to any adverse effects on catfish health.