It’s difficult to say why the respiration rate on your Brazilian seahorses (Hippocampus reidi) may have increased lately, but it was observant of you to notice the problem and it’s an early indication that something is amiss and should be corrected.
Some of your water quality parameters are off a bit, and I would begin by adjusting those. For instance, your specific gravity has crept up a little high and I would recommend gradually reducing it to 1.022-1.024. There is an inverse relationship between salinity and the dissolved oxygen levels in a marine aquarium (i.e., the higher the salinity the less dissolved oxygen the water can hold), so reducing the salinity of the aquarium will give the dissolved oxygen levels a little boost, which should be helpful.
Secondly, the carbonate hardness (KH) and calcium levels in your aquarium are also somewhat high. The optimum carbonate hardness for a marine aquarium is 7 dKH, which is the hardness of natural seawater. Likewise, a calcium level of 350-400 is the desirable range for a marine aquarium like seahorse tank that does not include a lot of live corals or other calcifying organisms, so I would recommend reducing the carbonate hardness and calcium levels in your tank.
An easy way to do that would be to stop buffering the tank temporarily and then to remove small amounts of the saltwater and replace them with unbuffered RO/DI water instead. The RO/DI water is very soft and will therefore help lower the carbonate hardness and the amount of calcium in the aquarium, at the same time it is reducing the specific gravity. So you can just remove small amounts of the saltwater in the aquarium and replace them with unbuffered RO/DI water until you have gradually lowered the specific gravity of your aquarium and the carbonate hardness and calcium levels have been brought down into the range I suggested above.
You didn’t mention the water temperature in your 37-gallon cube tank, Nova, but I would suggest maintaining a stable temperature in the 72°F-75°F range. The warmer the water, the less dissolved oxygen it can hold, so reducing the water temperature in the aquarium if it is higher than 75°F will also help to ease the breathing of your H. reidi seahorses. Lowering the water temperature will lower the metabolism of the seahorses, and therefore reduce their oxygen demand, at the same time as it is increasing the dissolved oxygen levels in your tank.
That is an excellent suggestion to add a hang-on-the-back protein skimmer to your seahorse tank, Nova. Your nitrate levels are right at the level where they begin to become a concern, and a protein skimmer will help to control nitrates by removing dissolved organics before they enter the nitrogen cycle. We never want to see nitrate levels much higher than 20 in a seahorse tank, and ideally we hope to keep them below 10 at all times. So please do invest in a good protein skimmer — as you said, it will help increase the aeration in your aquarium at the same time it is reducing the nitrate levels.
The waterfall return from the Cascade filter is great and will help provide good surface agitation to promote better oxygenation and efficient gas exchange at the air/water interface, but adding a protein skimmer will further increase the aeration, surface agitation, and water circulation in the aquarium, which is very desirable.
Although seahorses can certainly be kept successfully without the use of a protein skimmer, I recommend including a good skimmer for best results. As a rule, seahorses are messy feeders, particularly when scarfing down enriched frozen Mysis. Ample evidence of this is revealed every time they scarf one up. As they snick up a shrimp with their slurp-gun snouts, water is passed over their gills and expelled forcibly (it is this very process that generates the powerful suction they use to slurp up their prey). As the jet of water is ejected through their gills, it carries a cloud of macerated particles and debris with it. It is a startling sight the first time you observe this phenomenon, for it brings a fire-breathing dragon to mind. As one young hobbyist matter-of-factly described it, "My seahorse blows smoke out of its ears when he eats." I’ll be darned if that’s not exactly what it looks like, too!
The majority of the undesirable metabolites, organic wastes and excess nutrients that accumulate in our aquariums and degrade water quality are "surface-active," meaning they are attracted to and collect near the surface of a gas-liquid interface (Fenner, 2003). Skimmers take advantage of this fact by using a column of very fine air bubbles mixed with aquarium water to trap dissolved organics and remove them from our systems. This air-water mixture is lighter than the surrounding aquarium and rises up the column of the skimmer until the foam eventually spills into a special collection cup atop the skimmer, which can be removed and emptied as needed. Proteins and other organic molecules, waste products, uneaten food and excess nutrients, and a host of other undesirable compounds stick to the surface of the bubbles and are carried away along with the foam and removed from the aquarium (Fenner, 2003a). As a result of this process, these purification devices are typically known as foam separators, foam fractionators, air-strippers, or simply protein skimmers.
In my experience, nothing improves water quality like a good protein skimmer. They provides many benefits for a seahorse setup, including efficient nutrient export, reducing the effective bioload, and increasing both the Redox potential and dissolved oxygen levels in the water (Fenner, 2003a). They do a tremendous job of removing excess organics from the aquarium, including phenols, albumin, dissolved organic acids, and chromophoric (color causing) compounds (Fenner, 2003a). Their ability to remove dissolved wastes BEFORE they have a chance to break down and degrade water quality makes them indispensable for controlling nuisance algae. A good protein skimmer is an invaluable piece of equipment for keeping your nitrates low and your water quality high when feeding a whole herd of these sloppy eaters in a closed-system aquarium.
When it comes to skimmers, both the AquaC Remora and Euro-Reef series of protein skimmers are first-rate units that will serve you well. You can’t go far wrong if you select a quality AquaC or Euro-Reef skimmer rated for an aquarium of at least 40 gallons. I’ve also heard good things about the H.O.T protein skimmers. I believe Premium Aquatics (http://www.premiumaquatics.com) carries all of those brands of hang-on-the-back protein skimmers, and I would select one of the above if I was you.
If space is at a premium as far as installing a protein skimmer goes, a lot of hobbyists like the Red Sea Prizm protein skimmers because of their sleek compact design.
I believe that gradually lowering the specific gravity, reducing the water temperature, adjusting the water chemistry as previously described, and adding a protein skimmer to your tank will increase the dissolved oxygen levels and ease the breathing of your seahorses, Nova.
If it does not — if the huffing of your H. reidi persists after you have made the adjustments and corrections I suggested — then you may want to give the affected seahorses a quick freshwater dip and/or a brief dip in concentrated methylene blue to see if that helps their breathing.
Here are the instructions for performing a freshwater dip.
A freshwater dip is simply immersing your seahorse in pure, detoxified freshwater that’s been preadjusted to the same temp and pH as the water the seahorse is accustomed to, for a period of at least 10 minutes (Giwojna, Dec. 2003). It doesn’t harm them — seahorses typically tolerate freshwater dips exceptionally well and a 10-minute dip should be perfectly safe. Freshwater dips are effective because marine fish tolerate the immersion in freshwater far better than the external parasites they play host to; the change in osmotic pressure kills or incapacitates such microorganisms within 7-8 minutes (Giwojna, Dec. 2003). A minimum dip, if the fish seems to be doing fine, is therefore 8 minutes. Include some sort of hitching post in the dipping container and shoot for the full 10 minutes with your seahorses (Giwojna, Dec. 2003).
If you will be using tap water for the freshwater dip, be sure to dechlorinate it beforehand. This can be accomplished usually one of the commercial dechlorinators, which typically include sodium thiosulfate and perhaps a chloramine remover as well, or by aerating the tap water for at least 24 hours to dissipate the chlorine (Giwojna, Dec. 2003).
If you dechlorinate the dip water with a sodium thiosulfate product, be sure to use an airstone to aerate it for at least one hour before administering the dip. This is because the sodium thiosulfate depletes the water of oxygen and the dip water must therefore be oxygenated before its suitable for your seahorse(s). Regardless of how you detoxify the freshwater for the dip, it’s important to aerate the water in the dipping container well beforehand to increase the level of dissolved oxygen in the water. Many hobbyists leave the airstone in the dipping container throughout the procedure.
Adjusting the pH of the water in the dipping container so that it matches the pH of the water in the aquarium is a crucial step. Ordinary baking soda (sodium bicarbonate) will suffice for raising the pH of the water. If there is too much of a difference in the pH, there is a possibility the seahorse could go into shock during the dipping procedure. Preadjusting the pH will prevent that from happening. If you will are unsure about your ability to accurately adjust the pH in the dipping container, avoid this procedure altogether or be prepared to monitor the seahorse very carefully or shorten the duration of the tip to no more than about 4 minutes.
Observe the horse closely during the dip. You may see some immediate signs of distress or shock. Sometimes the horse will immediately lie on its side on the bottom. That’s a fairly common reaction — normal and to be expected, rather than a cause for concern, so don’t be alarmed if this happens. Just nudge or tap the seahorse gently with your finger if it lies down on its side. Normally, the seahorse will respond to the slight nudge by righting itself again and calm down for the duration of the dip. However, if it does not respond, stop the treatment.
Most seahorses tolerate the treatment well and experience no problems, but if you see continued signs of distress — twitching, thrashing around etc. — stop the treatment.
After you have completed the dip and returned the seahorses to the aquarium, save the dip water and examine it closely for any sign of parasites. The change in osmotic pressure from saltwater to freshwater will cause ectoparasites to lyse (i.e., swell and burst) or drop off their host after 7-10 minutes, and they will be left behind in the dipping water. Protozoan parasites are microscopic and won’t be visible to the naked eye, but some of the other ectoparasites can be clearly seen. For example, monogenetic trematodes will appear as opaque sesame seeds drifting in the water (Giwojna, Aug. 2003) and nematodes may be visible as tiny hairlike worms 1/16-3/16 of an inch long. Other parasites may appear as tiny dots in the water. Freshwater dips can thus often provide affected seahorses with some immediate relief by ridding them of these irritating pests and can also aid their breathing by flushing out gill parasites.
And here are the instructions for performing a quick dip in methylene blue, if you feel that it’s warranted, Nova:
Commonly known as "meth blue" or simply "blue," this is a wonderful medication for reversing the toxic effects of ammonia and nitrite poisoning. Methylene blue transports oxygen and aids breathing. It facilitates oxygen transport, helping fish breathe more easily by converting methemoglobin to hemoglobin — the normal oxygen carrying component of fish blood, thus allowing more oxygen to be carried through the bloodstream. This makes it very useful for treating gill infections, low oxygen levels, or anytime your seahorses are breathing rapidly and experiencing respiratory distress. It is the drug of choice for treating hypoxic emergencies of any kind with your fish. However, methylene blue will destroy nitrifying bacteria so it should be used in a hospital tank or as a brief bath or dip only (if used in an established aquarium, it will impair the biological filtration and the tank may need to be cycled all over again).
Here is some more information that may be helpful if you need to treat with methylene blue after all:
If you can obtain the Kordon brand of Methylene Blue (available at most well-stocked local fish stores), the instructions for administering it as a very brief, concentrated dip are as follows:
For use as a dip for treatment of fungus or external parasitic protozoans and cyanide poisoning:
(a) Prepare a nonmetallic container of sufficient size to contain the fish to be treated by adding water similar to the original aquarium.
(b) Add 5 teaspoons (24.65 ml) per 3 gallons of water. This produces a concentration of 50 ppm. It is not recommended that the concentration be increased beyond 50 ppm.
(c) Place fishes to be treated in this solution for no longer than 10 seconds.
(d) Return fish to original aquarium.
When you administer such a dip, hold the seahorse in your hand throughout the procedure and time it closely so that the dip does not exceed 10 seconds.
And here are Kordon’s instructions for administering the methylene blue in a hospital tank if longer-term treatment seems appropriate to reverse more severe cases of nitrite poisoning and ammonia toxicity:
As an aid in reversal of nitrite (NO2-) or cyanide (CN-) poisoning of marine and freshwater aquarium fishes:
(a) Remove carbon filter and continue to operate with mechanical filter media throughout the treatment period.
(b) Add 1 teaspoon of 2.303% Methylene Blue per 10 gallons of water. This produces a concentration of 3 ppm. Continue the treatment for 3 to 5 days.
(c) Make a water change as noted and replace the filter carbon at the conclusion of the treatment.
See the following link for more information on treating with Kordon’s Methylene Blue:
Click here: KPD-28 Methylene Blue
If you obtained a brand of methylene blue other than Kordon, just follow the instructions the medication comes with.
One other tip, Nova: if you ever need to handle seahorses to administer first aid measures or treat them in a hospital tank, it’s best not to net them when you are manipulating the seahorse:
I do not like to use an aquarium net to transfer or manipulate seahorses, since their delicate fins and snouts can become entangled in the netting all too easily. I much prefer to transfer the seahorses by hand. Simply wet your hand and fingers (to avoid removing any of the seahorse’s protective slime coat) and scoop the seahorses in your hand. Allow them to curl their tail around your fingers and carefully cup their bodies in your hand to support them while you lift them out of the water. When you gently immerse your hand in the destination tank, the seahorse will release its grip and swim away as though nothing out of the ordinary has happened.
Composed of solid muscle and endowed with extraordinary skeletal support, the prehensile tail is amazingly strong. Indeed, large specimens have a grip like an anaconda, and when a 12-inch ingens or abdominalis wraps its tail around your hand and tightens its hold, its vise-like grip is powerful enough to leave you counting your fingers afterwards!
In fact, it can be quite difficult to remove an attached seahorse from its holdfast without injuring it in the process. Never attempt to forcibly detach a seahorse from its hitching post! When it feels threatened, it’s instinct is to clamp down and hold on all the tighter. When you must dislodge a seahorse from its resting place for any reason, it’s best to use the tickle technique instead. Gently tickling the underside of the tail where it’s wrapped around the object will usually induce the seahorse to release its grip (Abbott, 2003). They don’t seem to like that at all, and will quickly let go to move away to another spot. Once they are swimming, they are easy to handle.
If the Anthias is proving to be a persistent pest at feeding time, and making it difficult for the seahorses to get their fair share of the frozen Mysis, or is intimidating them from approaching the feeding station or getting physical with them at all, then it would certainly be a good idea to relocate him to your reef system and put an end to his brief reign of terror.
Best of luck restoring order to your seahorse tank and getting your seahorses breathing easy again, Nova!