|Straus, David - Dave|
Submitted to: North American Journal of Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/26/2006
Publication Date: 10/23/2006
Citation: Goodwin, A.E., Straus, D.L. 2006. Solid and liquid formulations of copper sulfate: Efficacy at high and low alkalinities. North American Journal of Aquaculture. 68(4):359-363. Interpretive Summary: There are several commercial copper products that are used to cure fish that are infected with a parasite known as Ich. We tested the toxicity of these products on channel catfish and on Ich. Channel catfish were put in different concentrations of 3 copper sulfate formulations to calculate how much it takes to kill 50% of the fish in each solution (this is called the LC50 value and it is used to compare toxicity of different chemicals). We wanted to see if this toxicity was related to what type of water they were in (low or high alkalinity). We also used 2 of the formulations to test their toxicity to free-swimming Ich and tested in the same manner. We found no differences in toxicity, therefore extension agents can tell farmers to use the cheaper formulation when trying to cure catfish that are infected with Ich.
Technical Abstract: To assess the efficacy of new commercial formulations, the toxicity to channel catfish Ictalurus punctatus of three copper sulfate formulations was compared at low (48 mg/L) and high (243 mg/L) alkalinities. The formulations were copper sulfate crystals dissolved in water, a commercially available liquid copper sulfate formulation, and copper sulfate mixed with citric acid (a weak chelator). The former two formulations were also used to determine the doses required to kill theronts of Ichthyophthirius multifiliis (Ich) in vitro. Both copper sulfate and the liquid formulation killed Ich theronts in vitro at concentrations well below the catfish LC50. Neither liquid copper sulfate nor copper sulfate plus citric acid appear to offer any advantage over plain copper sulfate and both forms are considerably more expensive than copper sulfate alone.