Hygiene management in aquaculture facilities is critical for fish health, production efficiency, prevention of cross-contamination and overall farm biosecurity. In intensive production systems such as trout farming, ponds, tanks, nets, scoops, transport equipment, hatchery units, water lines and auxiliary equipment require regular microbial load control.

Various chemical groups such as Chloramine-T, formaldehyde/formalin, hydrogen peroxide and peracetic acid may be used in the sector for different purposes. However, these chemicals do not have the same application profile. Some are associated with special technical applications such as live fish baths or egg treatment. Peracetic acid-based products, on the other hand, can be evaluated as a strong alternative especially for hygiene, biosecurity, equipment disinfection and microbial load control.

What is Peracetic Acid?

Peracetic acid, abbreviated as PAA, is a strong oxidative disinfection system consisting of peracetic acid, hydrogen peroxide, acetic acid and water. Due to its broad antimicrobial activity, rapid decomposition under suitable conditions and lower risk of persistent chlorinated by-products compared to chlorine-based disinfectants, it is preferred in various industrial hygiene applications.

For aquaculture facilities, one of the most important advantages of PAA is its ability to help reduce microbial load, improve equipment hygiene and increase the level of biosecurity between production cycles when used at appropriate application points.

Where Can PAA Be Evaluated in Aquaculture Facilities?

Peracetic acid-based products should be positioned most safely and practically in aquaculture facilities for areas where live fish are not present; in other words, for empty systems, equipment, surfaces and auxiliary equipment disinfection.

1. Empty Pond and Tank Disinfection

At the end of a production cycle or during batch changes, organic residues, biofilm and microbial load may accumulate in emptied ponds and tanks. Washing these areas only with water may not provide sufficient hygiene, especially when biofilm is present.

PAA can be evaluated for microbial load reduction in empty ponds and tanks after pre-cleaning. This application is important for interrupting disease cycles, improving biosecurity during batch transitions and preparing production areas for reuse.

2. Hygiene of Nets, Scoops, Screens and Auxiliary Equipment

Nets, scoops, screens, separators and other contact equipment may create a cross-contamination risk when transferred between tanks or production areas. Cleaning these items after each use and treating them with a suitable disinfectant is important for internal farm biosecurity.

PAA-based products may be evaluated for disinfection of such equipment, especially after mechanical cleaning and pre-rinsing. Reducing organic load is one of the key conditions that improves PAA performance.

3. Transport Tanks and Shipment Equipment

Live fish transport tanks, oxygenation systems, hoses, pumps and connection parts are critical equipment in terms of hygiene before and after shipment. During transport, there is a risk of pathogen transfer between different production areas or different facilities.

Therefore, PAA may be evaluated as a biosecurity tool for disinfecting empty transport tanks and auxiliary shipment equipment. After application, rinsing, ventilation and active substance control are recommended.

4. Hatchery Equipment

Hatcheries are among the most hygiene-sensitive areas in aquaculture production. Egg trays, incubation channels, screens, water distribution components and auxiliary equipment should be regularly controlled for microbial load.

PAA may be evaluated in this area particularly for equipment hygiene. However, if direct application on eggs is planned, this should not be considered as a standard surface disinfection process. Species, developmental stage, contact time, concentration, water temperature and local regulations must be evaluated separately.

5. Pipes, Channels and Drainage Areas

In aquaculture facilities, piping systems, water distribution channels, drainage points and low-flow zones are risky areas for biofilm formation. Biofilm is not only a source of microbial load, but may also reduce disinfectant efficacy and protect pathogens.

PAA may be evaluated for biofilm and microbial load management in these areas during empty-system or between-cycle cleaning periods. In closed-loop systems, however, the biofilter structure requires a more cautious approach.

6. Evaluation in RAS and Closed-Loop Systems

The use of PAA in Recirculating Aquaculture Systems, known as RAS, requires special attention. In closed-loop systems, the biofilter is a critical component for ammonia and nitrite management. Therefore, the potential impact of PAA on the biofilter must be evaluated before application.

The safest initial approach for PAA in RAS systems is not to recommend routine dosing while live fish and active biofilters are in operation, but to evaluate it for empty-system cleaning, between-cycle system reset and controlled pilot application.

7. Footbaths and Equipment Transition Points

Personnel, equipment and auxiliary tools may cause microbial transfer within the facility. Therefore, footbaths, equipment disinfection points and controlled hygiene practices are important between production areas.

PAA-based products may be evaluated as part of biosecurity practices in these areas with appropriate concentration and contact time. Solution replacement frequency and active substance control are important for the reliability of the application.

8. Processing, Preparation and Auxiliary Work Areas

Surface hygiene is important in fish processing, cutting, preparation or auxiliary areas before packaging. PAA is one of the oxidative disinfectants evaluated in the food industry for surface and equipment hygiene.

For food-contact surfaces, product suitability, application concentration, contact time, rinsing requirement, active substance residue and local regulations must be considered separately.

Key Advantages of PAA

Important Notes on PAA Use in Water Containing Live Fish

The fact that PAA is being investigated as a water disinfectant in aquaculture does not mean that it can be applied directly and routinely to water containing live fish in every facility. In live fish applications, fish species, fish age, stocking density, water temperature, pH, alkalinity, organic load, dissolved oxygen, contact time and system type are determining factors.

Therefore, the use of PAA-based products for live fish baths, direct dosing into production water containing fish or direct application on eggs cannot be managed with a standard surface disinfection approach. Such applications require expert evaluation, pilot trials, residue/active substance monitoring, fish behavior observation and regulatory review.

Colin Approach: General Hygiene Map + Process-Specific Guide

At Colin, our approach for aquaculture producers is to provide a general hygiene and biosecurity framework without requiring disclosure of the company’s trade secrets. When process-specific information is shared, a customized application guide can then be prepared.

Within this scope, PAA-based products should first be evaluated for the following areas:

• Empty pond and tank disinfection
• Hygiene of nets, scoops, screens and auxiliary equipment
• Transport tank and shipment equipment disinfection
• Hatchery equipment hygiene
• Microbial load control in pipes, channels and drainage lines
• Between-cycle system cleaning
• Footbaths and equipment transition points
• Surface hygiene in processing and auxiliary production areas

For applications such as direct use in water containing live fish, fish baths or direct application on eggs, standard recommendations should not be provided without knowing the facility’s process information, water parameters and target application purpose.

Importance of PAA Test Kits for Controlled Application

PAA is an active substance that decomposes over time in water. Its decomposition rate may vary depending on water temperature, organic load, metal ions, pH, contacted surfaces and system conditions. Therefore, knowing only the initial dose is not sufficient in PAA applications; monitoring the active PAA level during application is important.

In aquaculture facilities, PAA-based disinfection products should preferably be evaluated together with a PAA Test Kit. This allows the facility to monitor active substance levels during application, avoid unnecessary overdosing and manage the disinfection process in a more controlled manner.

Conclusion

Peracetic acid can be evaluated as a strong alternative in aquaculture facilities, especially for hygiene, biosecurity, empty system disinfection, equipment hygiene and microbial load control. In trout production, the safest and commercially most appropriate positioning of PAA is to avoid live-fish treatment claims and to focus on facility hygiene, auxiliary equipment disinfection, hatchery equipment hygiene, transport tank cleaning and between-cycle system disinfection.

For special applications involving live fish, eggs or RAS biofilters, a controlled technical protocol should be prepared instead of providing a general recommendation. If the customer does not wish to share process information, general PAA application areas can be presented; however, definitive application dose and method should not be recommended without knowing the process information, water parameters and target application purpose.