Clove oil and salt improve the transport conditions of carp

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By Milthon Lujan

Carp (Cyprinus carpio).
Carp (Cyprinus carpio).

Transfer or transportation of fish is often an event that induces stress. Imagine collecting the fish, placing them in tanks full of water, and keeping them for hours and hours during the transfer. It’s no wonder that their health and survival can be affected.

A new study delves into the world of common carp (Cyprinus carpio), a popular ornamental fish that undertakes long journeys to reach aquariums worldwide. Researchers from the Federal University of Viçosa set out to test the individual and combined effects of clove oil (Syzygium aromaticum) and common salt on stress levels and overall health during transportation.


Could these additives be the secret to ensuring healthy travels for carp? The results promise to shed light on best practices for navigating the sometimes turbulent waters of fish transportation.

Clove oil and common salt

Clove oil, rich in natural sedatives and antioxidants, helps fish relax during transportation by reducing the harmful effects of stress hormones. Studies show that it can work wonders for some fish species, assisting them in making the journey with less energy expenditure and improved immune function.

However, clove oil doesn’t have the same effect on all fish species. For some fish, it can be harmful, causing damage instead of calm. That’s why scientists are looking for ways to adapt its use, exploring safe and effective combinations with other additives such as salt.

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Salt helps fish maintain their internal balance during the journey. Freshwater fish can lose vital fluids and electrolytes when transported. Adding a small amount of salt to the transport water mimics their natural environment, alleviating the stress of osmotic imbalance and protecting them from harmful changes in their internal chemistry.


However adding too much salt to the travel tank can have the opposite effect on fish. Hence, finding the right balance is key. Researchers are exploring the ideal salt levels for different fish species, ensuring a comfortable and safe journey without overloading their delicate systems.

Ideal combination of clove oil and common salt

This study investigated the combined effects of different concentrations of clove oil and salt on carp, a popular ornamental fish that often endures long journeys.

According to the study, the transport of C. carpio caused changes in water quality, such as reduced pH and increased ammonia content. “Transport also promoted oxidative stress in fish, characterized by an increase in reactive species (NO) generation and damage to proteins (PC) and a reduction in SOD and CAT activity in the gills,” reported the researchers.

The main findings of the study were:

  • Clove oil alone can be risky: Higher doses cause an increase in ammonia levels in the water and oxidative stress in the fish’s gills and liver.
  • Salt alone is not the ideal solution either: While it reduces ammonia and stress hormones, it unexpectedly causes oxidative damage to the liver and gills.
  • The magic is in the mix: The winning combination turned out to be 5 mg/L of clove oil combined with 3 g/L of salt. This duo kept water ammonia levels low and the fish’s internal balance, both immediately after the journey and even 96 hours later.
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Application in aquaculture and the ornamental industry


This study paves the way for safer and more effective fish, particularly carp, transportation practices in the ornamental industry and aquaculture. By optimizing the use of clove oil and salt, we can create a more suitable environment for our finned friends, reducing stress and ensuring their health and well-being during their journeys.

Remember, the successful transport of fish depends on finding the perfect balance of additives. This study offers a valuable alternative for smoother transport, paving a healthy path for fish transfer worldwide.


According to the study results, the combined use of 5 mg/L of clove oil and 3 g/L of common salt proved effective and safe for transporting carp, resulting in better maintenance of water quality and the redox state of gills and liver in C. carpio during long-duration transportation.

The study was funded by the Brazilian Federal Agency for Support and Evaluation of Graduate Education (CAPES, Brasília, Brazil).


Jener Alexandre Sampaio Zuanon
Department of Animal Biology, Federal University of Viçosa
s/n, Viçosa, Minas Gerais 36570-900, Brazil.
Email: zuanon@ufv.br

Martins, K. V. B., Silva, S. B., da Silva Cardoso, A. J., Salaro, A. L., Ferreira, P. D. M. F., Freitas, M. B., & Zuanon, J. A. S. (2024). Effectiveness and safety of clove oil and common salt in the long-term transport of Cyprinus carpio. Aquaculture, 740532.

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