SOP Refresher: Decontaminating aquatics spaces

Cleaning is defined as the process of making free from dirt, foreign, and extraneous matter, whereas disinfection is the process of freeing from infection specifically by destroying harmful microorganisms. 

Appropriate cleaning and disinfection procedures in fish laboratories are crucial in preventing the spread of aquatic animal pathogens and minimizing the build-up of waste products and biologic matter.  

The disinfection procedures chosen must be effective and relevant to the individual needs of the laboratory. The cleaning and disinfection methods used by different fish laboratories may vary considerably. Routine disinfection may be reduced to a minimum if good management practices are implemented daily. When people, equipment or other materials enter or leave a lab, thorough disinfection should be performed. However, in the case of an outbreak of a notifiable disease, rigorous disinfection procedures are necessary.  

The first step in decontamination is a thorough cleaning of the facility to remove organic material.  Organic material can harbor bacteria and greatly reduce the effectiveness of most chemical disinfectants. The washing and disinfection procedures should at least include the following stages:  

  • Removal of solid waste, etc., followed by prewashing;  
  • Deep cleaning and washing;
  • Disinfection;
  • Rinsing

Cleaning records should be kept. 

All the equipment used for feeding, cleaning, and for removal of dead aquatic animals should be unique to each housing unit. Appropriate net cleaning and disinfection reduces or eliminates organic material and kills infective agents, reducing the potential of the net to transmit pathogens. Nets are used frequently to capture fish from different tanks for breeding or other manipulations and are the most likely the source of cross-contamination if not cleaned and disinfected correctly between uses. General disinfection can be accomplished by soaking nets and brushes for 5 minutes in bleach solution, commercial net cleaner or alternate disinfection solution, followed by fresh water rinse.  To ensure neutralization of chlorine, a sodium thiosulfate solution can be used. 

Dirty tanks should first be scrubbed with a stiff brush to remove the majority of the algae.   They are then placed in a diluted bleach solution for 4-24 hours or washed by hand, and then stacked until they are thoroughly dry. 

A multipurpose alkaline cleaner designed specifically for use in fish is an important first step in removing organic solids and biofouling. Virkon Aquatic is a common cleaning and disinfecting solution with efficacy against a broad range of fish viruses, bacteria, fungi, and molds. 

All products used for disinfection must be used and disposed of in accordance with the manufacturers’ recommendations and likewise any health and safety guidelines should also be closely adhered to. If a Safety Data Sheet (SDS) has not been supplied with the product we strongly recommend that a SSDS be obtained from the manufacturers’ website or from the suppliers of the product. 

The disinfectants must be stored in a way that presents no direct or indirect danger to animal and/or human health and the environment. 

Cleaning and disinfectant resources: 

All personnel should regularly wash their hands after working in the facility, and wear gloves when in contact with fish or water. One of the most common routes of infection in humans is through cuts or scrapes on hands or feet. 

Agents available for general disinfection of facilities and equipment include Mycobacterium sp. Always consult manufacturer for use and safety requirements.