Well, sir, whether or not macroalgae can serve as suitable hitching posts for large seahorses such as Gigantes (Hippocampus ingens) depends on the type of macroalgae to a large extent. For instance, a lush colony of Red Grape Caulerpa (Botryocladia) is almost always a veritable seahorse magnet, and the ponies love to perch amidst the Botryocladia and search through its fronds for pods and other small crustaceans. For this reason, a thriving colony of Red Grape Caulerpa makes a terrific natural feeding station for seahorses that they need no training at all to use. You can deposit whole, intact frozen Mysis that you have carefully thawed on the colony of Botryocladia and the densely packed fronds will collect and hold the Mysis in place, and the seahorses will eagerly search through the colony and slurp up the Mysis shrimp.
On the other hand, Maiden’s Hair macroalgae is pretty useless as a hitching post for large seahorses. All types of macroalgae are useful in a seahorse tank as a means of controlling and exporting excess nitrates and phosphates, but not all species of macroalgae make good perches for our ponies. I will discuss some of the more desirable species of macroalgae in more detail later in this post, Don, but first I wanted to provide you with the following information, which is what I usually advise home hobbyists about hitching posts
When it comes to hitching posts and decorations, seahorses in general tend to prefer perches that are bigger in diameter over skinnier ones that are a bit more difficult to get a good grip on with their tails, but other than that, it’s very difficult to predict what they’ll go for. I have noticed that tree sponges and tube sponges — both the real thing (which are difficult to keep healthy) and the lifelike artificial versions (a better choice for most tanks) — almost always seem to be particular favorites. Very often such sponges are bright red or yellow or brilliant orange in coloration, but I think it is the structure and texture of the sponges that attracts the seahorses more than the color.
Tree sponges in particular are genuine seahorse magnets and the ponies really do love them. They are usually brightly colored (red and orange shades are common) and their shape and texture seem to make them irresistible to seahorses as hitching posts. Very often, all the seahorses in the tank can be found clinging to the same tree sponge together, eschewing other nearby holdfasts that appear every bit as comfy and attractive to human eyes.
So selecting a colorful tree sponge or two may be an excellent way to stimulate color changes in your seahorses. Collectors will often find bright red or vivid orange seahorses living in beds of colorful sponges in the wild.
However, hobbyists need to be aware that live sponges do contain toxins and incorporate glassy spicules into their fibrous bodies in order to deter fish predators. (Many marine angelfish love to graze on sponges, and in some species sponges comprise the bulk of their diet.) But, as a rule, this never causes any problems in a seahorse tank because it’s entirely a passive defense mechanism — the sponges have to be attacked and torn open in order to release the toxins and that just never happens under normal aquarium conditions.
I can see how it might become a problem, however, if a sponge died undetected in the aquarium and began to break down or decompose, releasing its toxins in the process. As with many sessile life forms, it can sometimes be difficult to tell if a sponge is healthy and thriving or if it’s doing poorly and should be removed as a precaution. Live sponges do best in well-established reef tanks and often have difficulty getting enough to eat in a conventional community aquarium or seahorse tank, but usually the sponge colony will simply shrink in size as a result. If they become fungused or smothered under algae growth, it’s best to remove them as soon as possible. (Don’t try to scrape off the algae growth from a sponge or scrub it clean or cut away the affected portions of the sponge — all of those procedures could release the toxins into your aquarium with deadly results.) So when you keep live sponges, place them in areas with low light levels where they will receive moderate water flow to discourage algae grow. Or better yet, use a colorful lifelike tree sponge instead of the real thing, such as the ones offered by Ocean Aquaria (oceanaquaria.com).
Seahorses often tend to gravitate towards gorgonians as well, and the big purple gorgonians that are large in diameter are also usually very popular with seahorses. Otherwise, they seem to like genuine corals and synthetic corals about equally well. The colorful artificial sea rods and gorgonians provided by Living Color, in particular, are real seahorse magnets — every bit as popular with our ponies as tree sponges.
Pay special attention to the hitching posts you select for your seahorse tank. Strive for bright reds, oranges, and yellows — even shades of pink or purple — in anything your seahorses may adopt as a holdfast. These aquatic equines — especially the stallions — will often choose one particular hitching post as their home base and spend much of their time perched right there (think of your Dad hunkered down in his favorite easy chair in the den). Once they adopt a favorite base of operations like this, they will sometimes proceed to change coloration to match their preferred resting spot. So you want to encourage them to adopt one of the more vivid pieces as a favorite holdfast.
Mildred Bellomy provides a perfect example of how this works in the Encyclopedia of Seahorses:
Elizabeth Goetz of Miami, Florida has kept one or more seahorse stables in her home for many years. She wrote the following anecdote about one of her seahorses that "turned red with envy."
"About five or six years ago, it was just about this time of year, [Christmas], we began our holiday decorating. Our own is not the simplest place to decorate for special occasions in that we have so many aquariums — approximately 35 at the time. Fourteen of these tanks were the homes of seahorses (Hippocampus hudsonius). [Editor’s note: Hippocampus hudsonius is an outdated synonym for Hippocampus erectus.]
"After completing the superficial home decorating, we decided it would be a grand idea to really go all-out with the holiday scheme and include the aquariums. On checking through our collection of assorted Christmas bric-a-brac, we found a number of ceramic items suitable for display in sea water. There were Christmas trees in north-woods green, gaily ornamental angels lovely enough to have stepped from the very gates of Heaven, winged carolers, haloed mermaids, etc., and lo and behold! — one, red-robed, sitting Santa Claus, with the most adorable facial expression one could imagine. Here, then, was ample material to decorate to one’s heart’s content.
"The walls of the dining room are lined with 10- and 15-gallon aquariums so we chose the most prominent 15-gallon tank for this pixie-like Santa. This was the home of five seahorses and they, too, seemed really happy with the decorating idea. We will not argue the point that any other smooth ceramic piece would have pleased them equally, but it is more satisfying to believe that the seahorses joined in with the holiday spirit. Nevertheless, almost as soon as their former hitching posts were removed and a Christmas item put in its place, the seahorses wrapped their respective tails around the new items and were completely at home again. Though scientists may adamantly disagree, we firmly believe fish do have varied personalities, even within their own species. Ask any hobbyist. We have had friendly seahorses, unfriendly ones, and downright cussed critters; the timid, placid, bold, and boisterous, and all of these and more personality traits were observed in H. hudsonius alone.
"All of the foregoing is merely to set the stage for our tale of the seahorse that turned red with envy.
"Our little seahorse star of this story was the most calm and timid of the five in our Santa aquarium. He would cruise calmly from his hitching post for exercise and return to his own station a short distance from the Santa, never trying to usurp the throne of another of his tankmates. The others did claim Santa as a resting place. Seldom was the time when Santa didn’t have the tail of a seahorse wrapped gently around an arm that rested on his pack, or around the tipped-up tassel of his toboggan. Our calm but "envious one" would stare in Santa’s direction almost constantly, while resting. It might be well, at this point, to emphasize that Santa was the only red-colored object or part of this aquarium. This previously dark (brownish) seahorse — originally colored the same as the other four — turned bright red. His change occurred gradually, over a period of about a week and it is quite true, he became a most beautiful red for the holidays."
Now we are well aware of color changes in nature, assumedly for protective measures, and being mindful of the fact that this timid little fellow did not cling to red-robed Santa, but remained some distance away, what then could the whimsical-minded, season-inspired person presume other than that the most peace-loving seahorse in the aquarium bathed himself in the reflected glory of the mythical man-of-the-hour, the one and only Santa Claus. <Close quote>
Notice that the seahorse reverted to its usual dark brown coloration when the scarlet-clad Claus figurine was removed from the aquarium after the holidays.
The moral of this story is that you can never tell what might catch your seahorse’s eye and trigger a corresponding color change in response to a change in its immediate environment. With that in mind, some hobbyists have experimented with brightly colored aquarium backgrounds and achieved surprising results. For instance, I have received reports that a bright orange aquarium backing can stimulate vivid color changes in some seahorses, although the result is often not what you would expect. (One wonders if Hippocampus perceives all colors the same way we do.) Don’t hesitate to experiment until you find the right combination that works well for both you and your seahorses.
If the aquarium you purchase comes with a choice of background colors, aqua blue is usually an option and is another color that is said to encourage seahorses to brighten up in coloration.
Transitory color changes can be achieved rapidly, in a matter of moments, but long lasting transformations occur gradually, and may take days to complete. This is often the case when a seahorse adopts a favorite hitching post and makes it his home base or center of operations. When that happens, the seahorse will often assume a color that closely matches its chosen resting spot so it blends in with its background when hanging out at headquarters. This is akin to the situation with the ceramic Santa; the color matching occurs slowly and, once the transformation is complete, the seahorse intends to keep its new coloration indefinitely.
Macroalgae — Living Hitching Posts
For live hitching posts, I prefer decorative marine plants or macroalgae in a variety of shapes and colors and color — reds, golds, and yellows in addition to green varieties, some tall and feathery, some short and bushy — to provide them with natural hitching posts and shelter. I like to start with a mixture of red and gold Gracilaria (Ogo), which grow well attached to rocks, and artfully arrange them around a lush bed of assorted bright green Caulerpa, which thrives in a sandy substrate. Any of the plumed (feathery) or long-bladed Caulerpa would be ideal for this, such as Caulerpa sertularioides, C. mexicana, C. ashmedii, C. serrulata or C. prolifera. But they may not be the best choice for tall tanks (or as hitching posts for large seahorses) since none of these species will grow more than about 4-6 inches in height at the most.
Be sure to thin out the fast-growing Caulerpa regularly; when you remove the excess strands and fronds, you’re exporting phosphates, nitrates and other nutrients from the tank, thereby helping to maintain good water quality, and thinning out the runners helps keep it from going sexual.
When thinning out Caulerpa and other macroalgae, take care not to actually cut it. Remember, you’re not pruning hedges or trimming trees — the idea is to carefully pull up and remove continuous, unbroken fronds or entire runners with numerous old fronds. Simply thin out the colony of excess strands, gently plucking up convenient fronds that can be readily removed intact.
Typically, the Caulerpa colony will put out horizontal runners or strands (i.e., the stolon of the plant) and a number of vertical leafy structures or "fronds" will sprout upwards from these runners. When I am thinning out a bed of Caulerpa, I try to weed out the older growth and pluck out whole runners complete with several feathery fronds so that I minimize any breakage when I remove the older plant material from the colony. In other words, rather than plucking off individual fronds at the attachment where they sprout from the runners, I prefer to extract an entire runner or strand together with all of its fronds, which allows me to remove more plant mass with as little breakage or damage to the entire colony is possible. Often there will be older strands and fronds that have separated from the rest of the colony naturally, and these are the best runners to target since there will be little or no breakage when they are removed. By regularly removing the older runners and the associated fronds, you can interrupt the life cycle of the Caulerpa and prevent it from going sexual. This is best done on a weekly basis to be safe, if the Caulerpa colony is growing rapidly.
A little breakage when thinning out the Caulerpa is fine, but cutting or breaking too many strands will result in leaching undesirable substances into the aquarium water as the Caulerpa’s lifeblood drains away. Too much cutting or breaking can thus sap the colony’s strength and cause die offs or trigger the dreaded vegetative events that judiciously thinning out the colony otherwise prevents.
The Caulerpa colony also dies off en masse after reproducing sexually, and the massive die off of Caulerpa for any reason can present a danger to the aquarium. There are undesirable substances leached back into the aquarium from the dying colony, and the resulting decay of a large quantity of organic matter all at once may trigger a bacterial bloom and subsequent drop in the dissolved oxygen level of the aquarium. The combination of these events can sometimes result in the loss of specimens or even crash the entire system.
Such a "vegetative event" is unmistakable because it will often turn the water in a small, closed-system aquarium milky white until the filtration begins to have an effect. If such an event occurs, the observant aquarist can often save the day by performing a series of water changes and employing activated carbon and other chemical filtration media to remove the harmful substances that have been released.
If you find it difficult to obtain Caulerpa (it’s illegal in some coastal areas) or you’re simply concerned about your ability to maintain and control of Caulerpa properly, just use a different forms of macroalgae that grows less rapidly instead and you can get the same sort of benefits at relatively little risk. In that case, some of the other macroalgae you may wish to consider are Gracilaria, Ulva, Codium, Chaetomorpha, and Chlorodesmis. Hawaiian Ogo (Gracilaria sp.) are bushy red-to-brown macros that do well under low light levels. Sea Lettuce (Ulva sp.) are deep green sheets of algae that do best under a little stronger lighting. Maiden’s Hair (Chlorodesmis sp.) are bright green tufts or clumps of very fine-bladed algal mats that grow attached to small rocks. Codium is another bright green algae with an attractive branching structure. All of these types of macroalgae are much less prolific and slower growing than Caulerpa. However, like all macroalgae, they should still be harvested periodically in order to export the excess nutrients they have consumed.
Aside from red and brown Gracilaria, which often make good hitching posts for seahorses, and the bright green Ulva and Maiden’s Hair, which are not suitable perches for our ponies, some seahorse keepers also like the Chaetomorpha turf algae or spaghetti algae, as it is also known. It can best be described as looking like the clumps of the colorful plastic grass we use to fill Easter baskets. It is popular because it is slow growing and doesn’t require the kind of pruning that Caulerpa needs, and because it comes loaded with microfauna: miniature feather dusters, copepods and amphipods, tiny snails and micro stars. In short, Chaetomorpha is another interesting marine plant that can add some extra variety to a lush bed of macroalgae. But it is rather unsightly and unkempt in appearance, and I prefer to use it in a sump or refugium rather than in the main tank. And the stringy Chaetomorpha spaghetti algae does not make a suitable hitching post for any but the dwarf varieties of seahorses.
If you are looking for colorful macroalgae that goes well with live rock and will provide good hitching posts for seahorses, then I think you might like the "red-on-rock" algae species offered by Inland Aquatics. They are more colorful and won’t overgrow or overwhelm your tank.
Other colorful red macroalgae that are well worth trying include Heymenia or Halymenia (commonly known as dragon’s tongue) and Botryocladia red grape algae, which is commonly known as red grape Caulerpa (even though it’s not a species of Caulerpa at all). The dragon’s tongue is a very attractive red species that either likes the conditions in your aquarium and thrives, or doesn’t like the tank conditions and disappears. When it thrives, it’s a beautiful red macroalgae that’s an asset to any aquarium. The distinctive appearance of these Botryocladia and its reddish coloration make it an aquarium favorite which is also useful since a large colony makes a good natural feeding station for seahorses. It does well when attached to the rockwork.
Maiden’s hair algae and sea lettuce (Ulva spp.) are bright green species of macroalgae that normally grow attached to rocks and are typically sold that way for aquarium use. They could also be placed amid your live rock where they would receive bright light. They are excellent for nutrient export purposes, but do not make good hitching posts.
If you are looking for marine plants to maintain in a sandy area of your tank, many species of Caulerpa, Merman’s shaving brushes (Penicillus spp), Udotea "sea fans," and Halimeda sea cactus are available, all of which are just anchored in the sandy bottom and will put out rhizoids or holdfasts to keep themselves in place. Other species of Halimeda are available that sprout from live rock instead, so that’s another option if you prefer.
But the Halimeda sea cactus, Penicillus shaving brushes, and Udotea sea fans are all calcareous macros that require high levels of calcium in order to thrive. To maintain them successfully, you will need to monitor the calcium levels, total alkalinity, and carbonate hardness of your seahorse setup, provide occasional supplements of calcium or Kalkwasser, and maintain the aquarium more like a reef tank than an ordinary saltwater system. The larger specimens of these calcareous macros will make good hitching posts for seahorses.
Codium is another green macroalgae that’s very attractive in the aquarium and very distinctive in appearance (with its branching structure, it looks more like some sort of green gorgonian or bushy seafan, rather than a species of algae). It can grow several inches tall and may develop a bushy branching crown several inches in diameter. The Codium thus makes a good natural hitching posts for seahorses (Peggy Hill, pers. com.) and is a good choice for a well-lit sandy area in the tank.
Some macroalgae are rootless and do not anchor in place. This is true of the Chaetomorpha turf algae or spaghetti algae, for instance. It grows in tangled clumps that look like nothing more than the colorful green Easter grass we use in our Easter baskets as bedding for the jellybeans, marshmallow chicks, and chocolate bunnies. Chaetomorpha is therefore not very aesthetic looking in your main tank, but you can’t beat it for use in refugia or algal filters because hordes of copepods, amphipods, and other microfauna love to shelter, feed, and breed in the tangled masses of the spaghetti algae.
Like the Chaetomorpha, different types of Gracilaria or Ogo are often cultured by tumbling them so that they are always in motion, exposing different areas of the plant masses to the sunlight and assuring that clean water circulates through them continually. Several different types of Gracilaria (red, brown, green) are available and are typically sold in clumps by the bag or the pound. They don’t have roots as such, of course, but if you wedge them in crevices in your live rock or anchor them in place with a small rock or piece of coral rubble, they will attach to a hard substrate and grow well under favorable circumstances. Again, like the Chaetomorpha, these balls or clumps of Gracilaria/Ogo are ideal for culturing copepods and amphipods in your sump or refugium, but they will also look nice in your main tank and can serve as convenient perches for the ponies once they take hold.
When it comes to the live macroalgae (living marine plants), you can get various species of Ogo (Gracilaria) from Ocean Rider, but for more color and variety, there are a number of other places to order suitable live plants online.
Seahorses also like live rock, particularly colorful pieces that are heavily overgrown with pinkish or purplish coralline algae. Aside from looking pretty, live rock also provides additional biological filtration (both nitrification and denitrification) for the aquarium and provides shelter and sight barriers that make the seahorses feel secure.
In short, special attention to the hitching posts you select when decorating your seahorse tank. Strive for bright reds, oranges, and yellows in anything your seahorses may adopt as a holdfast. These aquatic equines — especially the stallions — will often choose one particular hitching post as their home base and spend much of their time perched right there (think of your Dad hunkered down in his favorite easy chair in the den). Once they adopt a favorite base of operations like this, they will often proceed to change coloration to match their preferred resting spot. So you want to encourage them to adopt one of the more vivid pieces as a favorite holdfast whenever possible.
Okay, Don, that’s the quick rundown on natural hitching posts for seahorses.
Best of luck finding the perfect perches for Gigantes, sir!
Pete Giwojna, Ocean Rider Tech Support