Copper Sulfate: Solution or Threat? Exposing its toxicity to parasite management in fish farming
Fish are a source of food or nutrition and fish farming is a source of income and livelihood for people around the world. The increasing demand for fresh fish products is driving the growth of farmed fish production. This is expected to continue to increase along with the growth of the world's population.
The process of fish farming is not easy. Many challenges cause the failure of the cultivation process, one of which is interference from the presence of parasites that cause disease in fish, resulting in decreased productivity.
Diseases caused by these parasites have caused losses of around 40% in aquaculture production, at a cost of more than US$ 100 billion. Advances in disease management can improve economic sustainability, improve the livelihoods of producers, and contribute to the growth of fish aquaculture at the local, regional, and national levels.
Copper sulfate (CuSO4) has been used as a treatment to reduce infections caused by parasites in fish farming. However, excessive use has been reported to have the potential to cause toxic effects. Therefore, a safe concentration of copper sulfate needs to be carried out first before use.
The use of copper sulfate in fish farming
Copper sulfate is used globally in agriculture and aquaculture as an algicide and fungicide.Copper sulfate has long been used in many countries as a chemical treatment to control and treat diseases in aquarium fish and in freshwater and marine aquaculture. It is also used to remove snails from aquaculture ponds and to control unwanted fish that are predators or competitors to commercially farmed fish.
Copper sulfate has been used as a drug to prevent or treat fungal infections in largemouth bass (Micropterus salmoides) eggs. This is particularly useful in water environments with high alkalinity, where fungi tend to grow more rapidly.
Copper sulfate can have varying concentrations of copper ions depending on the type or formulation of the product sold on the market. The most common formulation used in aquaculture systems is copper sulfate pentahydrate (CuSO4.5H2O).
The first study to report lethal concentrations of copper sulfate for fish was conducted in 1863 by Penny and Adams, using goldfish (Carassius auratus). Since the 19th century, copper sulfate has been used in freshwater fish farming to control parasites.
The importance of copper sulfate toxicity testing in fish farming
The use of copper sulfate in aquaculture has been extensively studied worldwide. This research is important because a deeper understanding of this chemical treatment agent can help optimize its use to control and treat ectoparasitic infections in fish. With the right knowledge, copper sulfate can be used more effectively and safely in the aquaculture industry.
Before copper sulfate is used as a treatment for farmed fish, it is important to know the safe concentrations that are acceptable to a particular fish species. This is especially important because the recommended concentrations and durations of treatment for copper sulfate are often close to lethal levels for many fish species.
Acute toxicity testing is a common way to measure how dangerous a drug or chemical is to living organisms and to see if it can contaminate species that are important to the environment and industry.
Fish tolerance to copper sulfate varies by species. Some fish are very sensitive to copper sulfate and can die at very low concentrations, while others are more tolerant. Therefore, the lethal toxin level (LD50) for 50% of the fish population in 96 hours can vary, depending on the type of fish, the copper sulfate formulation used, and other factors related to the fish and its environment.
Rainbow trout (Oncorhynchus mykiss), the toxin level after 48 hours is 0.75 mg/L. For juvenile rabbitfish (Siganus rivulatus), the toxin level is more than 3.0 mg/L after 72 hours. Young grass carp (Ctenopharyngodon idella) has a toxin level of 2.01 mg/L after 72 hours, while for tilapia (Oreochromis niloticus) it is 40.6 mg/L after 72 hours.
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REFERENCES
Dias, M.T. (2021). Toxic, physiological, histomorphological, growth performance and antiparasitic effects of copper sulphate in fish aquaculture. Aquaculture, 535: 1-29. https://doi.org/10.1016/j.aquaculture.2021.736350.
Straus, D.L., Ledbetter, C.K., & David, L.H. (2020). Inhibiting fungus on largemouth bass eggs with copper sulfate and its toxicity to fry and juveniles. Journal of the World Aquaculture Society, 51: 214-223. DOI: 10.1111/jwas.1263.
