Weak Snick: Suspect Nutritional Myopathy In Syngnathids
You may have heard of ‘weak snick’, a common description of a clinical sign in syngnathids whereby attempts to feed appear weakened, that is, they don’t produce the nice ‘click’ sound you like to hear when healthy syngnathids strike at their prey. Multiple causes have been attributed to this particular clinical sign however in some severe progressive cases; this has been suspected to be due to a nutritional myopathy, which simply means a muscle disease caused by a nutritional imbalance.
The suspected nutritional myopathy can present in many ways including: lethargy, weak snick, inappetence, and in severe unresolved cases, death. Often times, affected animals will succumb to secondary infections (often bacterial or parasitic) as these animals become immunocompromised from stress and malnourishment and this can often obscure the fact that the primary problem is of a nutritional origin.
While the cause has not been confirmed in syngnathids, the primary suspects are oxidized fatty acids, particularly susceptible oxidation are highly unsaturated fatty acids (HUFAs) as well as deficiencies in vitamins E and C. and the mineral selenium. These factors have all been proven to cause nutritional myopathies in other captive teleosts. Despite having the adequate amount of fatty acids in a diet, if oxidized, these altered fat molecules cause damage to muscle tissue. In synganthids, it appears that the neck and tail (seahorses) muscles are specifically targeted. This may be to be due to the extensive use of these muscles; the neck muscles due to a high feeding frequency and the prehensile tail in seahorses.
Multiple feeding strategies can be implemented to prevent a nutritional myopathy. Varied food types are a great idea; whether this is feeding a combination of frozen and live sources of food (mysis, copepods, rotifers, etc.) depending on the age of your syngnathid. Unfortunately, often times, hobbyists and aquarists are limited to only one or two food types. In this case, it is extremely important to offer supplements, whether it is gut-loading live food and/or soaking frozen food. Even if you are able to offer a variety of sources of food, both live and frozen, supplements are advised due to nutrient loss from handling and processing in the case of frozen food and nutrient spectrum variation depending on your source of live feed. Avoid freezing and thawing, always thaw in the refrigerator and avoid refrigerating for more than one hour after the food has been thawed.
While there are many reasons to start supplementing despite never having issues, one good example of a reason, especially when always feeding a single source of frozen mysid, is that suppliers can change their product, whether it’s how they culture their product (what is fed), where they catch from or even shipping times, packaging and processing methods, among others. So many factors can affect nutrient quality and content, especially HUFA and fat soluble vitamins such as vitamin E. Supplementing gives you a bit of a buffer in case of temporary or long-term deficiencies in food choices for your syngnathids.
Supplements will vary greatly depending on what you can acquire in your location, however the important thing to remember is to try and optimize the quantity and quality of your HUFAs, vitamins and minerals, paying particular attention to vitamin E, selenium and potentially also vitamin C. Finally, always store your supplements as directed by the manufacturer.
About The Author
Dr. Véronique LePage BSc DVM MSc
Dr. LePage is a veterinarian with a special interest in aquatic animals and pathology. She is currently the owner of an aquatic veterinary consulting practice, associate veterinarian at Ripley’s Aquarium of Canada and Adjunct Faculty member at the Ontario Veterinary College.
Dr. LePage has published a number of scholarly articles on fish diseases, spearheaded 2 major fish disease surveillance projects in Canada and conducted extensive research on diseases of captive syngnathids. She has been involved in a number of other research projects including the investigation of type E botulism outbreaks on the Great Lakes, sea turtle conservation work in Kenya and disease investigations in fish pertaining to viral hemorrhagic septicemia virus, koi herpes virus and amyloid associated with neoplasia in tricolour sharkminnows.