I’m very sorry to hear that you lost your seahorse like that! All my condolences on your loss.
Yes, it is very likely that the temperature spike your aquarium experience contributed to the seahorse’ s respiratory distress and ultimately its demise. Elevated water temperatures increase the metabolism of your seahorses, and therefore their consumption of oxygen, at the same time that the rise in temperature is reducing the amount of dissolved oxygen the water can hold. That creates a dangerous situation for seahorses and may well result in respiratory distress and rapid, labored breathing.
However, it’s unlikely that your seahorse could have asphyxiated as a result without the other seahorse suffering the same fate, or at least showing some signs of rapid breathing. That makes me suspect that your seahorse died as the result of an infection of some sort (perhaps due to ectoparasites or possibly an underlying bacterial infection), which the heat stress contributed to by weakening the seahorse’s immune system, as described below.
Heat stress is especially debilitating and dangerous for seahorses due to a number of reasons (Olin Feuerbacher, pers. com.). For one thing, elevated temperatures can have a very detrimental effect on the immune system of fishes. This is because many of the enzymes and proteins involved in their immune response are extremely temperature sensitive (Olin Feuerbacher, pers. com.). Some of these protective enzymes can be denatured and inactivated by an increase of just a few degrees in water temperature (Olin Feuerbacher, pers. com.). So when seahorses are kept at temperatures above their comfort zone, their immune system is compromised and they are unable to fend off diseases they would normally shrug off.
That’s what I believe probably happened to your seahorse, Kira. Fortunately, it appears that the seahorse that died was weaker or more vulnerable for some reason than the seahorse that survived under the same conditions. It’s a very good sign that the survivor is eating well and showing no signs of respiratory distress whatsoever. Now that you have corrected the problem and brought your water temperature back down to 75°F, hopefully the seahorse that survived will remain unaffected. As long as she is not exhibiting rapid respiration or heavy breathing, or any other symptoms of a problem, I would not subject her to the stress of a prophylactic freshwater dip at this time.
You did very well to remove the hood and lower your water temperature, Kira, and it was also a very good idea to replace your filter and increase the water circulation in your aquarium. Those measures will certainly help prevent the recurrence of any such problems in the future.
However, I would like you to take a couple of other precautions as well. For starters, consider adding an ordinary airstone to your tank, anchored just beneath the surface of the water. That will add surface agitation, extra aeration, and promote more efficient gas exchange at the air/water interface. Unless you’re quite certain your system already has plenty of water movement, it is also advisable to add a small powerhead for extra circulation. Seahorses can handle more water movement than most folks realize, and you can always turn it off during feedings. Just screen off the intake for the powerhead as a precaution so it can’t accidentally suck up a curious seahorse.
Aside from your basic water quality tests (ammonia, nitrite, nitrate, and pH), Lori, I also recommend that you use a test kit for measuring the dissolved oxygen in your seahorse setup in the future. The reason for this is that a drop in the level of dissolved oxygen is a great early warning indicator that something is amiss in the aquarium, and can thus predict potential problems (and allow you to take corrective measures) BEFORE they become full-fledged disasters. For example, a drop in O2 levels could be an early indicator of overcrowding — a signal that your system has reached its carrying capacity. Or it may merely signal a rise in the water temperature due to a summertime heat wave or indicate that the tank is overdue for a water change and/or a thorough cleaning to remove excess organics and accumulated detritus. Or it could be telling you that your tank is under circulated and you need to increase the surface agitation and water movement.
The point is that checking the O2 levels in your aquarium can alert you to impending problems and allow you to do something about them before they have dire consequences. A drop in O2 levels is often the first sign of a water quality problem and it can tip off the alert aquarist that trouble is brewing before his seahorses are gasping for air in obvious respiratory distress. Checking the dissolved oxygen levels regularly is the next best thing to continuously monitoring the Oxidation-Reduction Potential (ORP) or redox of the water, which is a luxury few hobbyists can afford.
The Tetra Oxygen Test Kit (TetraTest 02) is an adequate liquid reagent test kit for fresh or saltwater with simple color scales for comparing readings that tests for 02 in the range of 2-14 ppm (the optimum dissolved O2 level is 6-7 ppm). It will cost you between $8.50 to $14 depending on where you shop and should be available at any well-stocked LFS. Salifert also makes a nice 02 Test Kit (their 02 Profi-Test) that will run you about $20.
In addition, I would like you to perform a water change in conjunction with a judicious aquarium cleaning, just as described in my previous post above. You should also pick up some methylene blue at your local fish store as soon as possible. It’s inexpensive and that’s a very useful medication for the seahorse keeper to have on hand in case of such emergencies.
Finally, I would like you to be sure to administer a daily dose of beta-glucan (a potent immunostimulant) to boost the immune system of your surviving seahorse. This can easily be accomplished simply by enriching frozen Mysis with Vibrance (both Vibrance formulations now include beta-glucan as a primary ingredient) and feeding your seahorse as usual.
The research on the health effects of Beta Glucan is pretty phenomenal. It has long been used in the aquaculture of commercially valuable food fishes and seafood, such as cod, turbot, salmon and shrimp. It improves the growth rate and reduces mortality rates among the fry (or larvae in the case of shrimp), and improves disease resistance in juveniles and adults.
Not only should Beta Glucan help keep healthy seahorses healthy, it should also help ailing seahorses recover faster. Research indicates that it helps prevent infections and helps wounds heal more quickly (Bartelme, 2003). It is safe to use in conjunction with other treatments and has been proven to increase the effectiveness of antibiotics (Bartelme, 2003). It will be great for new arrivals recovering from the rigors of shipping because Beta Glucan is known to alleviate the effects of stress and to help fish recover from exposure to toxins in the water (Bartelme, 2003) .
For more information on the potential benefits of Beta Glucan for aquarium fish, please see the following article:
Click here: Advanced Aquarist Feature Article
In the meantime, keep a close eye on the surviving seahorse and let us know immediately if she goes off her feed, develops any breathing difficulty, or shows any other symptoms of a possible health problem. Be prepared to perform a diagnostic freshwater dip and/or a brief bath and methylene blue if the survivor begins to exhibit respiratory distress.
Best of luck with your seahorses, Kira!