METHODS TO MITIGATE DISEASE SPREAD THROUGH AQUACULTURE SYSTEMS

Jessie M. Sanders, DVM, CertAqV*
 
 Aquatic Veterinary Services
 4061B Soquel Dr
 Soquel, CA 95073
 cafishvet@gmail.com
 

Managing disease outbreaks can require time, money and energy. Using pre-emptive strategies to mitigate the possible spread of disease can be relatively cheap and easy. No matter the species or disease in question, simple changes throughout the production facility can have important impact on your bottom line.

Fish, and other aquatic organisms, live in a continually contaminated environment. It is impossible to completely sterilize their environment to limit the spread of disease. However, decreasing their stress level goes a long way to improve their immunity. The stress response in fish is very similar to the stress response in mammals. The hormone cortisol is released in events of acute or chronic stress and results in decreased immune function over time. Decreased immune function leads to more frequent disease and parasite outbreaks, potentially resulting in loss of product to morbidity and death.

The most significant contributor to fish stress is water quality. This can be one of the hardest aspects of production to manage depending on your setup and water source. No matter the source of your water, be sure to test it independently from your fish systems. All of your systems need to be tested regularly and more frequently for systems that are undergoing or recently completed chemical treatment. Stocking density can severely affect water quality between systems and needs to be carefully considered when moving animals in confined containers.

Stress from transport and handling can also have major impact on fish health. Fish are not made to be handled in any fashion, so limit the amount of times fish are moved between systems or physically handled for measuring or vaccination. Consider different methods of transport between systems. Could your transport be improved to limit stress? Try to think through the eyes of a fish to see if taking on new technology could benefit your final product.

Immune stimulants are becoming more readily available in aquaculture. Studies involving vitamin C, beta glycans and allicin are showing positive signs in feeding trials. Consider adding an immune stimulant to your fishes' feed in anticipation of a stressful event (i.e. handling, transport, etc) for the best result.

There are many potential benefits to anticipating fish stress and limiting it where you can. True, not all sources of stress can be eliminated, but limiting them will yield larger, healthier product with a robust bottom line.