Wow, that’s a very nice collection of corals and invertebrates you have assembled and it sounds like they are all thriving! I’m glad to hear that you’re elephant ear mushroom coral has been a model citizen so far and cause no problems for any of its tankmates. It may be that your particular elephant ear mushroom happens to be a species that is relatively harmless — that’s the trouble with common names, you can never be sure exactly which specimen you are talking about if all you have to go by is its common name. As you know, there are great many different types of mushroom corals, most of which are completely innocuous in the aquarium. The dangerous species — the one you must watch out for in the aquarium, particularly if you’re keeping seahorses and other small, bottom-dwelling fishes — is Amplexidiscus fenestrafer.
Your sponges and macroalgaes, gorgonians, clove polyps and zoanthids are all perfectly safe with seahorses, but several of your other corals are not. The sun polyp coral (Tubastrea spp.), Alveopora coral, and plate coral are all LPS corals which have large fleshy polyps that can deliver potent stings. Likewise, the fuzzy or hairy mushroom corals have more powerful stings than ordinary mushroom corals that are harmless. This does not necessarily mean you need to exclude these corals from your exhibit if you will be adding seahorses to the aquarium. Seahorses will learn to avoid them, and providing stinging corals are properly placed in the aquarium, seahorses will often do well with one or two carefully chosen LPS corals. But an aquarium crowded with LPS corals could certainly be problematic.
If you want to try keeping seahorses in an aquarium with lots of LPS corals, Carrie, you must take special precautions to seahorse-proof your reef system before you introduce the seahorses. When designing a reef tank that will include seahorses, one must anticipate the different ways they might be injured in such a setup and then take precautions to prevent them from coming to harm. The process of rendering your reef system seahorse safe is much like the measures new parents take to childproof their house when they are expecting their first child. Intake tubes for the filters should be shielded, siphon tubes should be equipped with filter baskets or screens, and so on…
For instance, when powerful water movement is combined with overflows, there is a risk that seahorses could become pinned against an overflow or even go over it (Delbeek, Oct. 2001). Therefore, in the seahorse reef, overflows must be baffled and/or screened off, or the water flow should be adjusted sufficiently to prevent that from happening.
Likewise, although seahorses have no problem with strong currents in the wild, in the confines of aquarium, it is possible for them to come in contact with stinging corals if they are struck by a sudden powerful wave or surge, or are overwhelmed by a strong, unexpected current (Delbeek, Oct. 2001). The hobbyist needs to take this into consideration when placing water returns and corals in the seahorse reef, particularly if species with powerful nematocysts such as Euphyllia torch corals, or Catalaphyllia elegant corals, or other LPS corals will be part of the exhibit (Delbeek, Oct. 2001). If possible, keep the water currents steady and unvarying so the seahorses can establish holding areas in the sheltered spots and low flow zones without getting blindsided by unpredictable currents.
One good way to accommodate both the needs of corals that prefer powerful currents and the seahorse’s need for slack-water retreats is to create tall rock formations a foot or two down current from the strongest water flows to intercept and deflect or divert that strong flow of water, creating eddies and slack-water zones where there is relatively little water movement down current. Seahorses will hold in these low flow areas when they want to move away from the current, so it’s a good idea to position convenient hitching posts in the lee or down-current side of such formations..
Another excellent way to accomplish the same thing is to use small powerheads to create and direct current wherever needed. A properly positioned powerhead can thus bathe your prized Acropora formations in a brisk water stream precisely without generating too much water movement elsewhere in the aquarium. Just be aware that powerheads can become death traps for seahorses if their intakes are not properly shielded or screened off, and take the necessary precautions (Delbeek, Oct. 2001). Carefully conceal the intakes amidst the rockwork where they will be completely inaccessible to seahorses, otherwise shield them, or screen them off with a sponge prefilter.
So you must be sure to monitor the seahorses closely in a tank with LPS corals at first in order to assure that there are no strong currents that could sweep the seahorses against the corals. And to be safe and eliminate all risk, most seahorse keepers would eliminate such corals from their setups.
Also, Carrie, you should be aware that although zooanthids and colonial polyps in general are safe for seahorses, they can present a risk to both the aquarist and each other. So you must be sure to observe a couple of precautions when handling the zoanthids and placing them in your aquarium.
First and foremost, many of the commonly available Zooanthus (button polyps) and Palythoa (sea mats) species contain a very toxic substance in their mucous coat known as palytoxin, which is one of the most poisonous marine toxins ever discovered (Fatherree, 2004). Palytoxin can affect the heart, muscles, and nerves, resulting in paralysis or possibly even death, and many hobbyists have reported numbness, nausea and/or hallucinations after merely touching these corals (Fatherree, 2004). When you handle zoanthids and palythoans, you cannot help picking up some of their protective slime on your fingers, and so much as rubbing your eye, picking your nose, or a small cut on your finger can be enough to land you in the hospital. When handling Zooanthus are Palythoa species, it’s very important to wear disposable latex gloves, avoid touching your mouth or eyes, and carefully dispose of the gloves immediately afterwards (Fatherree, 2004).
Secondly, zoanthids and other soft corals such as mushrooms may wage border battles if you place them in close proximity to each other (and the zoanthids almost always lose out to the mushrooms in these skirmishes). So be sure to allow adequate space between the colonies. Some rapidly growing Zooanthus colonies can be aggressive to soft and stony corals alike as they rapidly spread over the rockwork, but in general they are quite peaceful, and you can always slow down their rate of growth by reducing the nutrient loading in the aquarium.
In short, Carrie, it’s best to avoid any stinging animals with powerful nematocysts when establishing a modified reef system that will include seahorses. This means fire corals, anemones, and any corals with polyps that feel sticky to the touch must be excluded. When a seahorse brushes up against them or attempts to perch on them, the nematocysts or stinging cells of these animals can penetrate the seahorse’s skin and damage its integument. Needless to say, this causes pain and discomfort and can leave the seahorse vulnerable to secondary bacterial and fungal infections, which may take hold at the site of injury. Soft corals and small-polyped stony (SPS) corals are generally acceptable, but large-polyped stony (LPS) corals must be regarded with caution. These include genera such as Catalaphyllia, Cynarina, Euphyllia and Trachyphyllia that have large fleshy polyps which often have tentacles equipped with powerful stinging cells.
For more details, please see the following post on this forum which discusses seahorse-save corals and how to set up a suitable reef tank for seahorses in considerable depth:
Click here: Seahorse.com – Seahorse, Sea Life, Marine Life, Aquafarm Sales, Feeds and Accessories – Re: eahorse/zoanthid tank.
Also, be sure to check out the following two Horse Forum columns which discuss keeping seahorses in reef tanks. They are available online on this site at the following URL’s:
Best wishes with all your fishes (and invertebrates), Carrie! (By the way, great work lining up the Diamox — that’s the hardest of all the medications to obtain.)