The use of copper to control fungus and bacteria in aquaculture has been in use for many years; however, the price of copper has risen > 650% since the year 2000. Additionally, copper has become less available due to government-controlled monopolies of mineral mines outside the US. Zinc is ~1/3 the price of copper yet the two elements share many chemical properties and behave competitively for protein binding sites. We evaluated the ability of Zinc sulfate to kill several bacteria relevant to finfish aquaculture: Streptococcus iniae, Flavobacterium covae, Flavobacterium columnare, and Aeromonas veronii. Using minimum inhibitory concentration (MIC) assays to compare the antibacterial effect of copper and zinc, we found the MICs of copper and zinc to be similar with copper being slightly more potent against Gram negatives and zinc being more potent against Gram positives. We additionally compared the acute toxicity of CuSO4 and ZnSO4 in Largemouth Bass fry and found zinc to be slightly less toxic. Follow up research is underway to develop on-farm usage procedures.