Guidance

Biosecurity measures (disinfectants, non-chemical methods etc.)

Updated 16 April 2025

Applies to England and Wales

Consideration needs to be given as to what is the biological risk that needs to be protected against. Some pathogens or invasive species require a particular approach or disinfectant.  Some disease such as notifiable viral diseases are capable of surviving dried on hard surfaces for several weeks.  For general use against a wide range of biological risks disinfectants are more likely to be effective.

Disinfectants will vary in the effectiveness in terms of contact time (the time they require to be in contact to render an organism inactive), some may be just a few minutes, some much longer.  Ones that require longer contact times may affect how you apply them; a spray application may not provide enough contact time and so an immersion/bath application is required.

Some disinfectants are only ‘active’ for short periods of time. Peracetic acid/Peroxide based disinfectants are only active for 10 – 30 minutes before they break down and are no longer effective, therefore needs to be considered in their application.

Other disinfectants may have significant risk in their use in terms of safety to the person using them and the environment for disposal.  For example, sodium hypochlorite (bleach) is a strong bleaching agent and also releases chlorine gas and so should always be used with adequate protection and in a well-ventilated area, sodium hydroxide (caustic soda) is extremely caustic and can cause burns to contact with the skin or eyes and may damage certain materials it comes into contact with.  Whatever disinfectants are used, manufacturers guidance on their safe use must always be followed.

Another factor to consider is that few disinfectants have been tested against aquatic diseases, a disinfectant listing scheme exists to provide assurance in tested effectiveness against serious aquatic bacterial and viral disease.  These disinfectants have been designed for use in aquaculture or by use of fishery owners and anglers.  They are available from suppliers direct, online suppliers or from equine/agricultural suppliers.

Aquaculture disinfectant listing scheme: apply or view - GOV.UK (www.gov.uk)

In addition to specific aquaculture or recreational fishery disinfectants, there are also more general disinfectants or methods that can be used:

1. Chemical methods

• Sodium chloride (salt) solution 3% (30g/litre of water) (approximate equivalent to the salinity of seawater) – effective against freshwater parasites.
• Sodium hypochlorite 0.25% (25ml/10litres of water) for 2 min. *
• Sodium hydroxide (caustic soda) solution 0.2% - raising above pH12. **

*Eye damage, skin irritation, toxic to aquatic life

**Severe skin burns, eye damage

2. Non-chemical methods

• Freshwater – effective against marine parasites.
• Complete drying for at least 2 days at 0 degrees C (minimum)
• Deep freezing for at least 1 day
• Exposure to heated water at 40 °C for 5 minutes (temperature needs to be maintained through this period). a simple and effective means of killing parasites)

3. Disinfectant Solutions

You should use a clean water source to dilute the disinfectant. If this is not possible, lake water can be used but make sure you increase the disinfectant dose to maintain efficiency.

Then you should:

3.1 1. Work out the volume of the disinfectant container you will be using with the following equations:

• square or rectangular container: Length (cm) x Width (cm) x Depth (cm) = Volume (l).
• round container: 3.14 x Radius2 (cm) x Height (cm) = Volume (l).

3.2 2. Use the total volume of the container to calculate the amount of disinfectant as per the manufacturer’s instructions.

• disinfectant required: Volume (l) x dose rate per Litre = total amount.

3.3 3. Fully mix the disinfectant into the solution.

4. Monitoring disinfectants

Disinfectant dips need to be monitored and are harder to monitor without specialist equipment therefore, this should be considered when choosing which product to use. For example, some produce test strips to ensure the concentration is adequate for disinfection purposes. Whilst others can be monitored due to colour changes, when the solution’s colour fades, the effectiveness is reduced and the required contact time increases.

5. Disposal of disinfectant solution

Care should always be given as to the disposal of disinfectant solution and manufactures guidelines should be followed.  Disinfectants must not be disposed of in water courses or areas that animals may have access to.