Rats! I hope the Diamox pouch flush does not traumatize your stallion and take too much out of him. Try to flush out his pouch as thoroughly as possible with clean saltwater before you inject the Diamox into his marsupium.
Regarding how long it may take to see positive results from the praziquantel if the weak snick is related to protozoan parasites, Carol, that is very difficult to say. There is really no way of predicting how long it will be before problems with weak snick run their course. The hyperplasia and swelling always take time to resolve themselves, even after the ectoparasites have been eliminated. The healing process must take place at its own pace, and many times seahorses or seadragons will struggle with weak snick for several weeks or even a matter of months before they have recovered fully and resume feeding on their own again.
The key to successfully resolve the the problems with weak snick and related feeding disorders (e.g., sticky trigger, trigger lock, or lockjaw) is to provide the seahorse with nutritional support until the healing naturally occurs. Sometimes this can be accomplished simply by providing softbodied adult brine shrimp that have been enriched, which are easier for the seahorses to slurp up, even in their impaired state (unsuccessful, in your case, Carol). But sometimes it requires force feeding the seahorses, which may involve hand feeding them individual Mysis one at a time on a daily basis or tube feeding the seahorses in extreme cases.
So the prognosis varies and I hesitate to suggest any particular timetable by which you should expect results. Aside from trading for a potential parasite problem, there is one other thing you can consider in cases of weak snick that sometimes appears to be helpful, but it can also be very problematic for seahorses, so I do not recommend it except as a last resort. It is a last-ditch alternative that some hobbyists have used successfully, as explained below:
Treating Weak Snick with Melafix
Treatments for protozoan parasites and ciliates don’t always resolve cases of weak snick. Freshwater dips and baths in formalin or other chemotherapeutics such as malachite green do a good job of eliminating free swimming protozoans and parasites on the surface of the fish, but aren’t helpful in eliminating embedded parasites, especially if they have invaded the buccal cavity and the esophagus of the seahorse. And, of course, not all cases of weak snick are associated with protozoan parasites. Some cases involve mechanical injuries to the underlying musculature that operates the seahorse’s suctorial feeding mechanism, and secondary bacterial and/or fungal infections resulting in hyperplasia or granulomas may be involved in some instances.
There is one other thing you might consider by way of treatment, however. I have heard several anecdotal reports from hobbyists over the years who have had good success treating this kind of feeding disorder using Melafix. For example, I have heard from two hobbyists who reported that Melafix cured seahorses with weak snick, and from another aquarist who had a good outcome using it to treat a seahorse with a sticky trigger problem. This suggests that Melafix can sometimes be helpful in treating the category of related afflictions hobbyists variously refer to as weak snick, sticky trigger/trigger lock, and lockjaw, all of which affect the seahorse’s suctorial feeding mechanism.
It appears that the Melaleuca tree oil in the Melafix is soothing to the injured or irritated muscles and tissue and can help promote healing, so that’s something that you may want to consider, but only if you observe all of the necessary precautions, as explained below. Be aware that Melafix can cause death by asphyxiation in seahorses if the proper precautions are not taken, which is why I only recommend using it as a last resort.
Even when the Melafix is helpful, it is very difficult to project how long it may take for the affected tissue to heal in a situation like yours. Much depends on whether the injury/infection involved the powerful sternohyoideus muscle that runs from the hyoid bone to the cleithrum and operates the buccal suction pump, or the hyohyoideus muscles and dilator operculi muscles which work together to operate the opercular suction pump, or both sets of muscles, and how severe the injury/irritation or strain happened to be.
So as long as none of your seahorses are experiencing any kind of breathing difficulties or respiratory distress, you might consider treating your tank with Melafix to help speed the healing process. As I said, I’ve heard a few anecdotal reports from hobbyists that maintain they have cured seahorses with weak snick or "sticky trigger/trigger lock" using Melafix (i.e., Melaleuca tree oil). It’s a risky treatment for seahorses due to the potential risk of asphyxiation, but it may have some limited application for feeding disorders that affect the seahorse’s suctorial feeding mechanism.
By and large, the people who have used Melafix to treat seahorses report that it seems to be a very safe product but it only useful for treating minor problems and superficial injuries. It is a very mild medication, and its main virtue seems to be that its reef safe and can be used to treat the main tank. Reef keepers apparently like it because it is safe to use with delicate corals and invertebrates, and won’t impair the biofiltration, so they can use to treat fishes in their reef tank that would otherwise be difficult or impossible to catch and remove for treatment in a hospital tank.
My main concern with Maleluca tree oil, the active ingredient in Melafix, is that it may impair the breathing of seahorses under certain circumstances for a couple of reasons. First of all, it seems to stimulate excess mucous production, and may cause the gills to be coated with a layer of slime. Secondly, it reportedly causes a drop in oxygen (O2) levels during treatment.
The drop in O2 levels is definitely a cause for concern, particularly if excess mucous production is impairing respiration by causing the gills to be coated in slime at the same time. If a thin film of this oil covers the surface of the aquarium, that could interfere with efficient gas exchange at the air/water interface, resulting in a drop in O2 levels and a build up of CO2. And that could account for the demise of a specimen that’s already been weakened by weak snick interfering with its ability to feed normally. One property of the Maleluca tree oil is that it dramatically reduces the surface tension of the water, causing protein skimmers to go nuts and overflow with copious amounts of wet foam. Skimmers usually need to be shut off during treatment as a result, so maybe that reduces the oxygenation in the aquarium further.
Perhaps at the least we can say that Melafix is contraindicated in cases where the affected seahorse is experiencing respiratory problems. It sounds like it is never advisable to use Melafix when seahorses are huffing, exhibiting labored breathing, or showing any signs of respiratory distress. And it would certainly be a sensible precaution to increase the aeration, surface agitation, and circulation when treating with this product. Consider adding an extra airstone or two to be safe.
If you are treating with Melafix and you notice a change in the seahorse’s breathing — any signs of respiratory distress — I would discontinue the treatments immediately and remove the medication from the water ASAP. Start up your protein skimmer, resume filtration with activated carbon, and perform a water change right away.
I will also avoid adding Melafix to any aquarium which is being treated with other medications. Don’t use Melafix if there are already other medications in the aquarium water!
That’s all that I can suggest under the circumstances, Carol. If you try the Melafix, be very careful to take all the necessary precautions to prevent a drop in the dissolved oxygen levels and potential problems with asphyxiation.