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United States Department of Agriculture

Agricultural Research Service

Title: The Acute Toxicity of Copper to Blue Tilapia in Dilutions of Settled Pond Water.

Author
item Straus, David

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 30, 2002
Publication Date: April 2, 2003
Citation: STRAUS, D.L. THE ACUTE TOXICITY OF COPPER TO BLUE TILAPIA IN DILUTIONS OF SETTLED POND WATER.. AQUACULTURE. 2003. v.219. p.233-240.

Interpretive Summary: Copper sulfate is a medicine used on fish to keep them from dying when they get a disease called Ich. Blue tilapia were exposed to copper sulfate in an aquarium to determine how much it takes to kill them. The aquariums were filled with settled pond water or settled pond water diluted with deionized water; the dilutions were 100%, 50%, 25% and 6.25%. (This is similar to diluting pond water with rainwater). It takes a lot more copper to kill blue tilapia in 100% pond water than in the diluted waters. This is because copper reacts with other compounds in pond water and these compounds are less concentrated when the water is diluted. This experiment shows that blue tilapia can tolerate more copper than other types of fish like channel catfish or rainbow trout and that copper sulfate treatment in the more diluted waters may kill the fish.

Technical Abstract: Blue tilapia fingerlings (Tilapia aurea) were exposed to copper (Cu) in a series of static toxicity tests. The water used in this study was composed of settled pond water or settled pond water diluted with deionized water. Estimates of mean 96-hr LC50 values (median lethal concentration) were 43.06, 6.61, 0.69 and 0.18 mg/l Cu (as copper sulfate) in waters having total alkalinities of 225, 112, 57 and 16 mg/l CaCO3, respectively. These data demonstrate the typical acute toxicity response of Cu, in which toxicity to tilapia increases as pH, total alkalinity and total hardness decrease. The results indicate that blue tilapia are relatively tolerant to Cu when compared to other species and that copper sulfate treatments in low alkalinity waters may be detrimental to the health of blue tilapia.

Last Modified: 9/20/2014
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