SOMETHING FISHY

Biosecurity considerations for your aquatic animal set-up

BY DR SASHA SAUGH

Biosecurity refers to the practices and procedures

used to prevent the introduction, spread and persistence of an infectious agent. Different environments and management practices present varying levels of disease risk to animals. Maintaining biosecurity involves managing this risk not eliminating the risk (which is not possible). The aim is to remove conditions that make animals more susceptible to disease. Biosecurity practices should be practiced by exporters, importers, wholesalers, retailers, producers, hobbyists and anyone involved in managing aquaria.

Why is biosecurity so important? It benefits every level in the supply chain and decreases the risk of diseases being passed on through different levels. It is, therefore, an important part of any business plan which involves animals. Biosecurity is not limited to intensive production systems involving aquatic animals, but to all levels of animal husbandry. The outcomes of good biosecurity practices translate to fewer production losses; improved health and welfare of animals concerned; less cost due to veterinary treatments or other interventions; and, often overlooked, is the improved reputation within the ornamental fish industry and with clients who source aquatic animals from you.

A good biosecurity plan will focus on three key concepts, i.e., keeping the pathogen (microscopic organisms that cause disease) out, containing the pathogen, and the application of good health practices.

Pathogens could enter through animals and parasites they carry, plants, the water source, people involved with handling and care of the aquatic animals, the animal’s housing system, and any equipment or instruments that make direct or indirect contact with aquatic animals or their water source. Animals may not show symptoms of disease, and one should not assume that animals that appear healthy are not carriers of infectious diseases. Suppliers that should be used should ideally: have a reasonable track record of supplying healthy fish; provide references from satisfied customers to support claims of providing quality products; source animals from a limited number of trusted sources with animals from each source housed separately with separate water systems; conduct disease screening on their animals to identify diseases; work with veterinarians not just when health problems arise, but as part of health screening, husbandry and biosecurity management; and have a biosecurity program that they are willing to share with clients. Beware of claims of fish being certified free of disease. Diseasefree certification applies to a specific disease/s and is supported by sampling and testing in accordance with specific protocols. No certification guarantees healthy animals.

Looking at water sources: municipal water sources may have varying quality which could predispose animals to diseases. If well water is used, it should be tested for bacterial contamination, heavy metals, chlorine, and high levels of dissolved gases. With surface water, there is a high risk of it containing pathogens, therefore it should be tested for bacteria, as well as chemical contamination. Water used in transporting animals should not mix with water of any aquatic system unless first treated, except if it is a quarantine system.

Food as a source of pathogen entry: good quality commercial diets will unlikely contain infectious agents. The reputation and history should be evaluated when choosing feed suppliers. Feed should be evaluated for spoilage and contamination. For live feed, pretreatment or quarantine should be considered due to the higher risk of pathogen entry with these. Storage areas should be free of vermin, and cold and air-tight storage should be People (staff, customers, etc.) that come into contact with infected aquatic animals, or their water, could have pathogens on their hands, body or clothing, which can then be a source of infection to other aquatic animals, water, feed and equipment. Appropriate decontamination procedures and protective gear should be used. Appropriate decontamination procedures, in the same way, should be applied for equipment or instruments that are used off-site or in different areas of the facility.

Quarantine is an important biosecurity measure to prevent pathogen entry. It also allows animals to recover from transport and handling stress, and to acclimatize to new environmental conditions and management. Animals that should be quarantined are new aquatic animals; aquatic animals from other facilities, the wild or from farms; and those returned by customers. Fish from separate sources should be quarantined separately. Plants and invertebrates being potential carriers of pathogens and parasites, should be quarantined as well.

It is important to consider the various routes of pathogen transmission, viz. waterborne, airborne, vector (living organisms), fomite (inanimate objects), and feed transmission. Waterborne transmission, discussed above, can be addressed through mechanical filtration, chlorine treatment, ultraviolet light treatment, ozone treatment or a combination of these. The risk of airborne transmission increases where holding tanks or ponds are located close together without solid covers or dividers. Transmission occurs through water splashes and contaminated water droplets in mist form can contaminate various surfaces, include nearby ponds or tanks. Using solid tank covers or splash guards between housing systems, as well as reducing splashing where possible, will decrease the risk of aerosol transmission. Vector transmission, which occurs mostly through invertebrates (which include parasites and various chemicals), can be used in control and prevention. Transmission through fomites such as nets, buckets, brushes, siphons, pumps, scrapers, vehicles, etc., occurs due to improper handling and disinfection procedures. Any fomite exposed to aquatic animals, their housing system (including the water), and other contaminated surfaces, requires disinfection. Fish feed could be contaminated by pathogens or toxins, which include live, fresh or frozen feed. Food should be evaluated for food spoilage (e.g., damp, mouldy, malodorous).

When implementing good health practices, the aim is to provide an optimal environment for animals to resist infection and one that reduces stressors on animals. A visual assessment of animals should be done every day to assess for signs of disease, distress or abnormal behaviour. Where necessary, animals should be isolated for closer observation and/or treatment. Housing systems should be easily viewed and accessed for cleaning and maintenance, with enough hiding spaces, with no edges or objects that could injure animals, and with life support systems that are easy to manage and service. Staff attending to more than one system should practise appropriate sansitisation and disinfection between systems for equipment, hands, boots and other clothing.

Depending on what your set-up is, ideally standard operating procedures, record keeping, training, and accountability should be practised to ensure that good biosecurity is implemented.

Pet owners are encouraged to enquire about the source of their animals, and whether biosecurity practices are applied by suppliers to animals being traded. Facilities working with aquatic animals and pet owners should ideally have a biosecurity plan specific to their setup drawn up in consultation with a vet, knowledgeable on aquatic species. This is over and above basic biosecurity practices that are standard for typical aquatic animal systems. These do not need to be complicated or onerous, but practical and simple to follow. Biosecurity measures do change as circumstances change and as finances allow for certain provisions.

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Dr Sasha Saugh