The problem you’re describing is commonly referred to as "weak snick," an ailment that occurs when there is something wrong with the buccal suction pump and/or opercular pumps that generate the powerful suction with which seahorses feed. The buccal pump is the hyoid bone trigger mechanism seahorses use to slurp up food with a sudden inrush of water, while the opercular pumps move the water taken in while feeding or breathing past the gills and out again via a tiny pore that acts as an exhaust port. When these mechanisms are impaired, seahorses may have difficulty feeding and breathing, which leads to an assortment of odd ailments ranging from weak snick to sticky trigger to trigger lock to lockjaw.
These unusual afflictions are sometimes caused by mechanical injuries to this feeding mechanism, or secondary infections that involve the underlying musculature, but are more often due to parasites which invest the gills and gradually spread to the esophagus and buccal cavity, as discussed below in greater detail. Please read through the following information and see if it could apply in your case, Jeff:
Weak snick is an unusual affliction that results when a seahorse is unable to generate adequate suction to feed properly. Seahorses develop weak snick when their sophisticated feeding apparatus, or the muscles that operate it, are incapacitated as a result of injury or infection.
For example, I have often seen it in seahorses as a result of protozoan parasite infections (Amyloodinium, Cryptocaryon, Brooklynella, Uronema, etc.). I tend to suspect that’s the cause when the weak snick is accompanied by rapid respiration and labored breathing, or when more that one seahorse develops the condition, or when the weak snick victim’s tankmates are bothered by odd ailments such as "trigger lock," appetite loss, lockjaw, heavy breathing, or the first signs of snout rot, which all early indications of masked protozoan parasite infections (Giwojna, Dec. 2003). These organisms typically attack the gills first, from which they spread to the throat and mouth (oral or buccal cavity). As their numbers build up in the gills and they spread from within, invading the esophagus and oral cavity, symptoms such as rapid breathing, loss of appetite, weak snick, trigger lock, and snout rot begin to appear (Giwojna, Dec. 2003).
This is how I believe the disease progresses in such cases: the burrowing of the embedded parasites causes hyperplasia of the underlying tissue, and when sufficient numbers of them build up in the gills, we see the initial symptoms of respiratory distress, labor breathing, and huffing (Giwojna, Dec. 2003). During a heavy infestation, the parasites may attack the key muscles that expand the opercular cavity, or sheer numbers of the parasites can clog the gills to the extent that the opercular pump is impaired, resulting in weak snick due to a decrease in suction (Giwojna, Dec. 2003). In severe cases, this will eventually result in death by asphyxiation.
In less severe cases, the parasites will continue to spread from the gills into the throat, buccal cavity, and eventually the snout itself (Giwojna, Dec. 2003). When this happens, the irritation caused by the burrowing parasites and the hyperplasia of the infected tissue can cause loss of appetite or difficulty swallowing and the victim may go on a hunger strike (Giwojna, Dec. 2003). If the swelling and hyperplasia occlude the gills, throat and snout sufficiently to prevent the seahorse from generating adequate suction when attempting to feed, weak snick is the result (Giwojna, Dec. 2003). If the burrowing of the embedded parasites allows secondary fungal or bacterial infections to take hold, the seahorse can develop snout rot (Giwojna, Dec. 2003). When such secondary infection(s) affect the sternohyoideus muscle that controls the hyoid bone trigger mechanism, ailments such trigger lock, sticky trigger, or lockjaw result and again the seahorse is unable to feed (Giwojna, Dec. 2003). Weak snick can be caused in this way as well if the sternohyoideus muscle is affected to the extent that hyoid trigger still operates, but so feebly that the buccal pump can no longer generate sufficient suction to feed (Giwojna, Dec. 2003).
Another common cause of weak snick in many instances is a mechanical injury to the seahorse’s hyoid-bone "trigger" mechanism. This sometimes happens when a seahorse accidentally ingests a foreign object when feeding off the bottom. The offending particle is often a piece of gravel or crushed shell. When a hard, sizable foreign object such as this is ingested, it can lodge in the throat or snout, and the seahorse may have difficulty expelling it again. (The seahorse’s feeding mechanism is much better suited for sucking things in than spitting them out again.) When that happens, the seahorse is almost always able to clear the offending object eventually, but sometimes not before it causes considerable irritation or the repeated efforts to eject it cause a muscular strain to the hyoid trigger mechanism. The seahorse then acts as though it has a very bad sore throat. The suction it generates is weak and both the act of pulling the trigger and the act of swallowing appear to be painful. The seahorse feeds reluctantly or halfheartedly as a result, and may eventually stop feeding altogether. Such mechanical injuries can also open the door for snout rot.
Suspect a mechanical injury when the weak snick or sticky trigger is not accompanied by respiratory distress, when only one of your seahorses is affected and exhibiting unusual symptoms, or when you witnessed the seahorse struggling to expel a foreign object. In such cases, most often the problem clears up on its own after two weeks to two months as the injury heals. No treatment is necessary and the key to a successful outcome is keeping the patient eating while the healing takes place. That’s what treatment should concentrate on.
When these feeding difficulties arise, it’s a good idea to try tempting the affected seahorse with live adult brine shrimp. Seahorses suffering from weak snick induced by an injury may have better luck slurping up smaller, lighter, soft-bodied prey like brine shrimp; if so, that will be enough of to keep them going while they heal. You’ll want to enrich the brine shrimp to maximize its nutritional value, and gutloading the shrimp with an enrichment product high in HUFA such as Vibrance is a good way to fortify it beforehand. Brine shrimp are filter feeders that will ingest whatever is suspended in the water with them, so all you need to do is add a pinch or two (or drop or two) of the enrichment formula to a small container of saltwater swarming with brine shrimp at least 30 minutes before you offer the shrimp to your seahorse.
In short, Jeff, if you feel your seahorse’s weak snick is most likely the result of a mechanical injury, you need do nothing more than to keep it eating by offering it softbodied adult brine shrimp you have enriched beforehand. If the seahorse is experiencing respiratory distress or any other indications that suggest the problem could be due to protozoan parasites, there are number of treatment options you can consider.
For example, in that case, you could treat your seahorse with a 10-minute freshwater dip and/or a 30-60 minute bath in formalin. Both those procedures are very effective in eliminating ectoparasites and gilt parasites, and may provide your seahorse with immediate relief. Or you could try treating your seahorse in a hospital tank using acriflavine in conjunction with methylene blue. I will be happy to provide you with instructions for all of these treatment options in case you feel such a procedure or procedures is warranted in your case.
Best of luck resolving your seahorse’s feeding problem, Jeff! Here’s hoping he is soon slurping up frozen Mysis with his usual gusto again!