Re:Seahorse Regurgitates its meals

Dear Al & Cindy:

I’m sorry to hear about your male seahorse that is off its feed, sir. It is possible that the seahorse had some sort of an internal obstruction and that when he slurp up the frozen Mysis from the bottom of the tank, it temporarily blocked his esophagus until he was able to swallow it completely and caused him a great deal of distress in the meantime. But I think that’s rather unlikely, since such internal obstructions are very rare in my experience.

However, I have seen seahorses react just as you describe when they were feeding from the bottom and inadvertently inhaled a foreign object as well as the Mysis they were targeting. 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 such as this is responsible for the reluctant feeding when you witnessed the seahorse ingesting or 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 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.

Some hobbyists dealing with weak snick have had good success in coaxing the affected seahorse to feed by transferring the seahorse to a critter keeper or breeder net or similar enclosure that can hang within the main tank itself, and then adding a generous amount of live adult brine shrimp to the container. Within the enclosure, the affected seahorse does not have to compete with its tankmates for the live food, and it is easy to maintain an adequate feeding density within the confined space so that there is always a big juicy brine shrimp passing within striking distance of the hungry seahorse. Add one or two hitching posts within the critter keeper or breeder net so that your male can anchor in place and wait for a tasty brine shrimp to pass within easy reach, and give him an hour or two within the enclosure to eat him fill of the softbodied adult brine shrimp. You can monitor his progress from a nonthreatening distance away from the tank to see how she is doing. In most cases, the seahorse quickly becomes familiar with the routine of being transferred to the special enclosure at feeding time and associates it with tasty live foods and a full belly — positive reinforcements that make it a very nonthreatening, stress-free procedure for the affected seahorse — and, as a result, it may actually come to look forward to it after a few feedings. You can repeat this feeding process two or three times daily in order to fatten him up again, if your schedule allows.

On other occasions, Al, the offending particle that is accidentally ingested from the bottom is not an inert object at all but rather a small bristleworm. The bristleworms are also attracted to the uneaten frozen Mysis that settles to the bottom of the tank, and it is not at all uncommon for a hungry seahorse to accidentally slurp up a small bristleworm along with a piece of frozen Mysis when both the pony and the prickly pests were after the same piece of food.

As you can imagine, when that happens, the seahorse is temporarily traumatized, in great distress because of the irritating spicules on the bristleworm, and such an incident may make the unfortunate seahorse very reluctant to feed until the irritation has passed and any resulting injury has healed. If you have noticed any bristleworms in your seahorse tank, it’s possible something like this could be what is bothering your stallion.

In general, bristleworms are benign, even beneficial inhabitants of an aquarium that perform a useful service as scavengers. For example, although they are unwelcome hitchhikers in a seahorse setup, bristleworms are often considered to be desirable and valued as scavengers in reef tanks. The difference is that the nutrient loading in reef tanks is very low, which keeps the bristleworm population very well in check. The bristleworms tend to be relatively few and to stay relatively small in a reef system.

However, in a seahorse tank that received daily feedings of frozen Mysis, the abundance of nutritious food that is available can sometimes result in a population explosion of bristleworms. And when their numbers get out of control or they grow too large, there comes a point when an overabundance of bristleworms becomes problematic as far as seahorses are concerned. That point is generally when the exploding population of bristleworms become too large and aggressive at feeding time, actively seeking out the frozen Mysis even during daylight hours, no longer content with cleaning up leftovers, and begin invading the feeding station. Too many bristleworms lingering too long at the feeding station brings them in direct contact with the hungry seahorses who come to the lunch counter for their favorite food as usual. The galloping gourmets may accidentally brush up against the encroaching bristleworms, or even attempt to perch on them, and they may get a snootful of bristles when snicking at the same mysid a bristleworm has taken an interest in. Even if the seahorses don’t inadvertently snick at them, the bristleworms may shed a few of their irritating spicules while they are at the feeding station, and the hungry seahorses can then accidentally ingest such loose spicules when slurping up frozen Mysis. Captive bred seahorses are aggressive eaters that are accustomed to slurping up food from the bottom, and it seems at times this may also lead them to strike at baby bristleworms. I’ve also heard a few reports of seahorses that snicked up a tiny bristleworm and got them lodged in their snout or throat. It’s unclear in these cases whether the bristleworm was accidentally sucked up while the seahorse was targeting a piece of nearby Mysis or whether the seahorse actually mistook the tiny worm for something edible and deliberately struck at it, but this is another potential danger the seahorse keeper should be aware of.

I have seen pictures of seahorses with bristleworm spicules embedded in their tails and snouts as a result of such close encounters. These injuries are usually minor, easily treated by removing the spicules and administering antibiotics orally via gut-loaded shrimp to prevent secondary infections, but the more bristleworms there are, the more likely such incidents and problems are to occur.

I have seen a few seahorse tanks that were overrun by them to the extent that the bulk of the total biomass in the aquarium consisted of bristleworms! When that happens, they are detrimental simply because of their effect on the water quality. Under certain circumstances, the total metabolic activity of the countless bristleworms may have a greater impact on the nitrogen cycle that all of the seahorses and their tankmates.

So when you start to see bristleworms in your seahorse setup, it is a good idea to start thinning them out. It’s possible that your stallion may have accidentally slurped up a small bristleworm or ingested one or more spicules shed from a bristleworm, which are irritating’s snout, buccal cavity, or esophagus.

In short, Al and Cindy, it’s impossible to say for certain whether your male may have developed some sort of an internal obstruction or if it may have accidentally ingesting a foreign particle are even a tiny bristleworm well feeding on the bottom, and that that is what has triggered its reluctance to feed.

In either case, your best course of action is to try to keep the seahorse eating by offering it soft-bodied adult brine shrimp that are easier to swallow, as previously described. If you can keep the seahorse eating in this way as it gradually heals and recovers from the mechanical injury to its feeding mechanism, that’s often all that’s required for it to recover on its own.

In addition, it’s often a good idea to gutload the adult brine shrimp with a good antibiotic prior to feeding them to the affected seahorse, which will help to stave off any secondary infections that might result from an embedded bristleworm spicule or the abrasion from accidentally ingesting a foreign object.

Accidentally ingesting foreign objects is one of the reasons it’s best to train your seahorses to take their frozen Mysis from a feeding station or feeding tray, rather than allowing them to slurp up frozen Mysis from the bottom of the tank. Since the substrate is also where the seahorses’ fecal pellets and detritus tend to accumulate, it is far more sanitary and safe or for them to take their meals from a feeding station instead.

In fact, for best results, I recommend elevating the feeding station, which provides several benefits for our galloping gourmets:

(1) First and foremost, it isolates the feeding trough from the bacteria-laden substrate and provides the seahorses with a sanitary lunch counter from which to feed.

(2) Secondly, it keeps the feeding station beyond the reach of bottom scavengers such as bristleworms, Nassarius snails and hermit crabs, which are attracted to the frozen Mysis.

(3) Finally, it provides a sterile feeding surface for the ponies that is easy to remove and keep clean, thereby making it a breeze to dispose of leftovers, which safeguards your water quality. Keeping the feeding tray elevated makes it convenient to clean and sterilize between feedings.

Hopefully, your mail will be feeling much better tomorrow and resume feeding normally again, Al and Cindy. But if not, you’ll want to concentrate on maintaining optimum water quality in the aquarium, providing good surface agitation to promote better oxygenation and gas exchange at the air/water interface, which will ensure high levels of dissolved oxygen, and try feeding the affected seahorse with softbodied adult brine shrimp rather than the usual frozen Mysis.

Good luck!

Respectfully,
Pete Giwojna