Copper Sulfate in Aquariums

Copper sulfate crystals
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Copper sulfate is an inorganic compound that combines sulfur with copper that has been registered for use in the United States since 1956. It is widely used in agriculture as a fungicide in fruit and vegetable farming. It is available as a dust, wettable powder, and as a liquid.

Copper sulfate is also used for pyrotechnics, to create brilliant blue fireworks. It has been used as a dye and for electroplating processes. In aquaculture, it is used as an algicide and to treat parasites. It is not safe for use with any invertebrates.

Conditions that copper sulfate is used to treat include the following:

  • Ichthyophthirius multifiliis - Small white spots resembling sand or salt granules on the fish's skin. This is caused by a protozoa and causes the fish to scratch against objects. Use as a prophylactic treatment for quarantine tanks.
  • Other Protozoan infections
  • Removal of snails

Products Containing Copper Sulfate

Mardel Coppersafe 

  • Manufacturer's Directions for Use: Use 5 ml for 4 gallons of water. Loosen measuring chamber cap and squeeze bottle to fill to the desired level. One application treats water for one month. DO NOT overdose.
  • Active Ingredients: Chelated Copper Sulfate.
  • Benefit: CopperSafe is a chelated copper compound that is used for the treatment of infections of Ich (Ichthyophthirius in freshwater and Cryptocaryon in saltwater), Flukes (Gyrodactylus), Anchor Worms (Lernaea), Velvet (Oodinium) disease and other external parasites, according to the brand. CopperSafe, when used as directed, maintains a total copper level of 1.5 ppm to 2.0 ppm in the water. CopperSafe remains active for over one month in the aquarium. Levels of 0.3 ppm free copper are recommended in the literature for therapeutic use, but with Coppersafe, the levels of free copper will be measured at 1.5 ppm to 2.0 ppm. This level of copper can be used in the treatment of fish due to Coppersafe's unique chelating agent. The chelating agent binds with the copper making it nontoxic to fish, but effective against parasites. CopperSafe does not discolor the water and will not interfere with the biological filter
  • Use: CopperSafe should be used when a diagnosis of the fish's illness indicates the presence of Ich, Flukes (Gyrodactylus), Anchor Worms, Velvet Disease and other external freshwater parasites.


CopperSafe may be harmful to plants, amphibians, and snails, according to the brand. If possible, remove plants and invertebrates without an exoskeleton, such as jellyfish and anemones, from the aquarium. Otherwise, treat fish in a separate quarantine tank. Keep out of reach of children. For aquarium use only. CopperSafe is intended for the exclusive use with ornamental fish and/or ornamental organisms and is not intended for use with humans or fish for human consumption.

A chelated or total copper test kit is required to measure CopperSafe. Coppersafe may cause inaccurate free copper readings when using certain test kits. All readings should be based on the total copper or chelated copper results and not the free copper results.

Coppersafe is safe to use with UV sterilizers, protein skimmers, wet/dry and diatomaceous earth filters. After treatment, Coppersafe can be removed from the aquarium by water changes, fresh activated carbon, or other chemical filtration resins/pads.

CopperSafe comes in 100 ml, 250 ml, 500 ml, 2 liter and 20-liter sizes.

Seachem Cupramine 

Manufacturer's Directions for Use: Copper can be toxic to some sensitive fish species and is highly toxic to many invertebrates. It is safest to remove all invertebrates. Turn off UV sterilizer; remove chemical filtration during treatment.

For saltwater aquariums, if the bottle has a dropper cap, use 20 drops (1 mL) per 40 L (10.5 gallons) the first day, wait 48 hours, then repeat. On non-dropper caps, each inner ring is 1 mL. In freshwater, use half the saltwater dose. Final copper concentration is 0.5 mg/L in saltwater (0.25 mg/L in freshwater). Leave at this concentration for 14 days. Do not re-dose without testing levels using MultiTest Copper (DFS# 4343010).

Do not use in conjunction with any other medication. If the aquarium has ever been treated with an ionic copper (e.g. copper chloride, sulfate or citrate), test copper level after initial dosing. Although most fish tolerate Cupramine to 0.8 mg/L, it is not advisable to exceed 0.6 mg/L copper. Remove with activated carbon and water changes.

Article Sources
The Spruce Pets uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Use of Copper in Marine Aquaculture and Aquarium Systems. University of Florida Extension.

  2. CUPRAMINE- cupric sulfate anhydrous liquid. United States National Library of Medicine.