Black porgy swimming in a balanced aquaculture environment.

Ozone in Aquaculture: Is It Safe for Black Porgy?

Avery Sinclair in Science & Nature December 2025 • 4 min read.

"Balancing water quality and fish health in recirculating systems."

Marine finfish aquaculture in South Korea increasingly relies on recirculating aquaculture systems (RAS) to ensure stable production. RAS offers better control over environmental conditions, extending the optimal culture period and reducing the impact of external factors like temperature fluctuations and coastal contamination. However, the success of RAS hinges on effective water treatment, and ozone is emerging as a key tool.

Ozone's strong oxidation properties make it attractive for controlling pathogens, reducing solids, and improving overall water quality in aquaculture. But, while ozone can enhance water quality, it can also produce harmful byproducts known as total residual oxidants (TRO). The challenge lies in finding the right ozone dose that maximizes benefits without harming the fish.

This article breaks down a study on how different ozone doses affect black porgy (Acanthopagrus schlegeli) in RAS. The goal is to understand the impact of ozone on fish health, growth, and overall well-being, providing insights into safer and more sustainable aquaculture practices.

The Ozone Balancing Act: Benefits vs. Risks

Black porgy swimming in a balanced aquaculture environment.

The study evaluated black porgy in RAS with varying ozone doses: no ozone (control), 20 g ozone/kg feed/day, and 40 g ozone/kg feed/day. The 44-day trial monitored the fish for behavioral changes, growth, blood parameters, and histological alterations in their gills and livers. This comprehensive approach provides a detailed picture of ozone's effects.

Here’s what the study revealed:

Behavior and Mortality: No significant behavioral changes or mortalities were observed in the ozonated systems.
Growth and Blood: The ozone treatments didn't affect growth or blood parameters.
Histological Changes: Both ozone treatments caused histological changes in the gills and livers, with more pronounced cellular damage at the higher dose.

While the fish didn't experience immediate harm, the histological findings suggest potential long-term effects, indicating that the ozone dose needs careful management. The key takeaway is that an ozone dose should not exceed 20 g ozone/kg feed/day for black porgy in RAS, based on the histological results.

Optimizing Ozone Use in Aquaculture: Future Directions

The study underscores the need for careful ozone management in aquaculture. While ozone offers benefits like pathogen control and improved water quality, it's crucial to minimize potential harm to fish. Histological changes in the gills and livers of black porgy indicate that even seemingly safe ozone doses can have adverse effects.

To safely harness ozone's benefits in seawater RAS, future studies should focus on:

<ul><li>Long-term effects of TRO: Evaluating the cumulative impact of total residual oxidants on fish health over extended periods.</li><li>Optimal ozone doses for different species and life stages: Determining the specific ozone requirements for various aquaculture species and their developmental stages.</li><li>Mitigation strategies: Exploring methods to reduce TRO formation or minimize their toxicity in RAS.</li></ul>

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1186/s41240-017-0079-3, Alternate LINK

Title: Hematological And Histological Changes Of Black Porgy Acanthopagrus Schlegeli In Ozonated Recirculating Systems

Subject: Molecular Biology

Journal: Fisheries and Aquatic Sciences

Publisher: The Korean Society of Fisheries and Aquatic Science

Authors: Pyong-Kih Kim, Jae-Won Kim, Jeonghwan Park

Published: 2018-01-22

Everything You Need To Know

Why is ozone used in aquaculture RAS systems, and what are the concerns?

In recirculating aquaculture systems (RAS), ozone is used to control pathogens, reduce solids, and improve water quality due to its strong oxidation properties. However, using ozone in RAS can result in the formation of total residual oxidants (TRO), which can be harmful to aquatic life. Therefore, the correct ozone dose is critical to maximize the benefits of ozone while minimizing risks to the fish.

What were the main effects of ozone on black porgy observed in the RAS study?

The study showed that black porgy exposed to ozone in RAS did not exhibit significant behavioral changes or mortalities. Also, ozone treatments didn't affect growth or blood parameters. However, the histological examination revealed changes in the gills and livers of the black porgy, indicating potential adverse effects, especially at higher ozone doses.

Based on the study results, what is the recommended ozone dose for black porgy in RAS?

The key finding suggests that the ozone dose should not exceed 20 g ozone/kg feed/day for black porgy in recirculating aquaculture systems (RAS). This is based on the histological results, which showed more pronounced cellular damage at higher ozone doses. Therefore, an ozone dose of 20 g ozone/kg feed/day represents the optimal level.

What do histological changes in gills and livers mean for fish health?

Histological changes in the gills and livers of black porgy indicate that even seemingly safe ozone doses can have adverse effects. The study highlights that while ozone offers benefits like pathogen control and improved water quality, it's crucial to minimize potential harm to fish. While the study did not provide the complete details of the cellular damage, such damage can impair the fish's ability to respire efficiently (gills) and detoxify harmful substances (livers), affecting their overall health and resilience to disease.

Can the findings of this study be applied to other fish species in aquaculture?

This study focused on black porgy (Acanthopagrus schlegeli) and may not directly apply to other species. Different fish species may have varying sensitivities to ozone and total residual oxidants (TRO). Future research should investigate the effects of ozone on a broader range of aquaculture species to determine species-specific safe ozone levels and optimize water quality management in recirculating aquaculture systems (RAS).