AC Aqua (MTS Environmental Inc. Exeter, Ontario, Canada) is a natural liquid humic acid product. This substance is a non-toxic, environmentally friendly substance that could be used as a substitute for chemical and antibiotic treatments for diseases in channel catfish Ictalurus punctatus. Humic substances have been shown to have many effects, and there is increasing interest in using these products in the aquaculture industry. Exposure to humic acid can be beneficial for fish species. Rainbow trout (Oncorhynchus mykiss) eggs infected with the spores of Saprolegnia sp. have been shown to have significantly decreased mortality and increased hatching rates in the presence of humic acid. When humic acid is added to the diet of Arctic Char Salvelinus alpinus, the survival rates of fish exposed to Flavobacterium columnare increased significantly. Studies in channel and hybrid catfish have shown humic acid increases growth and improves the immune response when exposed to various bacterial pathogens. Therefore, the following research aims to assess the safety and efficacy of AC Aqua when used as a water treatment against Motile Aeromonas Septicemia caused by a virulent strain of Aeromonas hydrophila (vAh). The following objectives were investigated: 1) the effects of vAh growth on bacterial plates with humic acid added, 2) the effect of humic acid concentrations and treatment time on bacterial flocculation and settling rate, 3) the chemotactic response of vAh to catfish mucous and 4) detection of bacterial adhesion. Results of these objectives will be presented.