Re:macros/dwarf tankmates??

Pete Giwojna

Dear Kaitlyn:

It’s good to hear back from you again and I’m pleased that you have been able to establish the Ulva sea lettuce and Caulerpa in your dwarf seahorse tank.

And I’m sure you are correct — the dead rock that you added to your dwarf seahorse tank has no doubt become well colonized with beneficial nitrifying and denitrifying bacteria after six months, and can now provide the same benefits as live rock for your dwarf setup, without any risk of introducing unwanted hitchhikers such as hydroids, Aiptasia rock anemones, or bristleworms.

When it comes to attaching plants to the rockwork, the plants you are cultivating right now may be very difficult to establish on the rocks. Ulva and Caulerpa typically grow on a sandy substrate and may not colonize your rocks at all. You may want to try some other types of macroalgae for that purpose instead.

For example, Inland Aquatics offers several different types of macroalgae described as "red-on-rock," which would be worth trying in order to achieve the effect you are striving for; just purchase a colony of the red-on-rock macroalgae and place the rock it is growing on amidst the dead rock in your dwarf tank. If it likes the conditions in your aquarium, it will spread over the surrounding rocks as well.

For colorful red macroalgae, you may also want to consider Botryocladia, which is commonly known as red grapes or red grape Caulerpa (although it is not a species of Caulerpa). It’s very attractive, grows reasonably tall, and won’t take over your aquarium. Some species of Botryocladia grow well on rockwork.

Halymenia or dragon’s tongue is another attractive red algae species that is worth your consideration. Red Dictyota is yet another reddish macroalgae that grows tall rather than bushy, which you may want to try. There are a number of good sources where you can obtain colorful macroalgae for the aquarium, Kaitlyn.

For starters, Inland Aquatics has perhaps the best selection and variety of macroalgae available, including a number of red types:

Aquacon is another good source for cultured macroalgae:

Click here: Marine Plants for Saltwater aquariums

Be sure to check out as well — they offer a Red Macroalgae Sampler that includes a few different red species, and they also offer Botryocladia and Halymenia on occasion:

Regarding tank mates for dwarf seahorses, there are a number of companions that I have found do well with Hippocampus zosterae and that I could recommend without reservation. For example, for a nice splash of added color and natural beauty, I often like to add an assortment of Feather Dusters (Sabellastatre magnifica and Sabella sp.) amidst my beds of macroalgae. They are the brightly colored flowers blooming among all the greenery of this underwater garden. Feather Dusters are exotic, very showy, entirely harmless, relatively inexpensive, and completely compatible with dwarf seahorses (Giwojna, 2005). They are filter feeders and seem to eat the same newly hatched brine shrimp as dwarf seahorses, but they do best when fed phytoplankton (or commercial food preparations designed for filter-feeding invertebrates) with a baster from time to time.

The Lettuce Nudibranch (Elysia crispata, formerly known as Tridachia crispata, and still usually sold under that name) is another showy, totally innocuous invertebrate that’s a perfect choice for a dwarf seahorse companion. It is green with lavender spots and is covered with extravagant frills and ruffles that look like flower petals on an exotic orchid, but in fact they are the ruffled flaps of tissue (parapodia) that outline each side of the back of this two inch sea slug that lives in the waters of the Caribbean and Florida Keys (Giwojna, 2005). It’s an algae eater that dines on macroalgae such as Caulerpa sertularioides and is one of the few nudibranchs that do well in the aquarium, particularly a dwarf tank with a lush bed of Caulerpa (Giwojna, 2005). As long as you are cultivating Caulerpa in your dwarf tank, Kaitlyn, it could easily support one of the showy Lettuce Nudibranchs.

Although I have never tried them with my pigmy ponies, hobbyists tell me that there are are a couple of types of small, colorful shrimp that can also be kept safely with dwarf seahorses — namely, the beautifully marked Bumblebee Shrimp and Sexy Shrimp.

Sexy shrimp (Thor amboinensis) are colorful and get their common name from their curious undulating dance, which adds to their interest in the aquarium. Their dancing is entertaining to watch and they are peaceful little shrimp get along together in groups or colonies. These boldly marked little shrimp are safe to keep with even newborn dwarf seahorses, but I would fear for their safety in an aquarium with large seahorses such as Mustangs or Sunbursts (Hippocampus erectus). They are very small for shrimp — most specimens I have seen range from about 1/4 to 1/2 inch in length — and that makes them fair game for hungry seahorses. In the ocean, sexy shrimp are often found sheltering in anemones, just as clown fish do, but of course you would be kee go downhill ping them without a host anemone in your dwarf seahorse tank.

I’ve also been told that the beautifully striped Bumblebee Shrimp (Gnathophyllum americanum) is another good candidate for a dwarf seahorse tank. The bumble bees are colorful little crustaceans that like to eat the tube feet of echinoderms, and the specialized diet means they have no interest whatsoever in even the tiniest of dwarf seahorses. Aside from their peculiar culinary habits, they are tiny shrimp that never grow larger than an inch in length. Most specimens I have seen are between 1/4" and 3/4" in length, which means that large seahorses such as Hippocampus erectus may regard the little bumblebee shrimp as potential prey, although they make good companions for pigmy ponies.

Most starfish must be avoided when keeping dwarf seahorses because they are a threat to the pigmy ponies and their young, but there are a couple of exceptions to this rule. For example, the Red Bali Starfish (Fromia milliporella) is a small, nonaggressive starfish that feeds primarily on detritus and meiofauna on sandy substrates. The Red Bali Starfish is a tiny species that doesn’t grow to more than 3 inches in diameter (most aquarium specimens are only 1-2 inches in arm span). They thrive in a well-established aquarium with macroalgae and a sand substrate. (However, if you want to add a colorful little Fromia starfish to your dwarf seahorse tank, then you should avoid including any Bumblebee Shrimp, since the bumble bees like to feed on the tube feet of the seahorses. Dwarf seahorse keepers must therefore choose between the colorful Fromia starfish and the attractive Bumblebee Shrimp — they may include one or the other, but not both in their dwarf tanks.)

Also worth considering are the tiny brittle starfish commonly known as Micro-Stars and often marketed as aquarium scavengers or sanitation engineers under that name. They start small and stay small, with a leg span that never exceeds the diameter of a 25-cent piece even when they are fully grown (most of these miniature brittle stars cannot span a 5-cent piece). Their legs are often attractively banded and they are very active and agile scavengers, moving more like miniature octopus that slowpoke sea stars. The micro-stars are fascinating in their own right, but it’s best to limit yourself to one or two of them, since they reproduce very quickly when conditions are to their liking.

Those are some companions that you might consider adding to your dwarf seahorse tank, Kaitlyn.

Along with the tiny decorative shrimp and Fromia sea stars mentioned above, assorted snails can serve as the cornerstones of the clean-up crew for dwarf seahorse tanks. The snail assortment may include bumble bee snails, trocha snails, margaritas, Astrea and Cerith snails, etc., but I always make sure to include a few of the smaller species of Nassarius snails.

Nassarius snails are terrific detritivores and amazingly active for snails. They’ll bury themselves until they detect the scent of something edible, and then erupt from the sand and charge out to clean it up. But you must make sure that you obtained genuine Nassarius snails, and the species that usually works best is Nassarius vibex.

And you are right about the whelks, Kaitlyn — when you are considering Nassarius snails for a seahorse tank, you must be aware that they are often confused with whelks, which are active carnivores. Not only would the whelks pose a danger to the dwarf seahorses but they would also very likely predate the other snails in your cleanup crew as well. Whether as an honest mistake or perhaps as a deliberate deception, I have also found that some dealers market whelks as Nassarius snails, so the dwarf seahorse keeper must beware of this possibility. When you are purchasing the Nassarius snails, look for a dealer that offers Nassarius vibex snails and also includes a photograph of them. That way you can examine the photograph and make sure that the Nassarius vibex are not actually whelks masquerading as Nassarius snails.

Providing you get the genuine Nassarius vibex, you can be confident they will not be harmful to your dwarf seahorses in any way and make outstanding scavengers for your dwarf tank.

Yes, I have had good success with Scarlett reef hermits in my well-planted dwarf seahorse tanks. They are herbivorous by nature and typically occupy themselves chowing down on algae in the well planted aquarium. But no matter how harmless and small and inoffensive microhermit crabs may be, they are never completely trustworthy in every aquarium and every circumstance, so if you want to try Paguristes cadenati in your particular dwarf seahorse setup, keep a close eye on them at first and be prepared to relocate them if necessary.

This is what I normally advise hobbyists regarding microhermit crabs, Kaitlyn:

<Open quote>
Microhermit crabs are generally entertaining additions to an aquarium that do a great job as scavengers and get along great with seahorses, but over the years, I’ve had a few seahorses that were confirmed crab killers. These particular ponies were persistent hermit crab predators that specialized in plucking the hermits out of their shells and attacking their soft, unprotected abdomens, and they honed their skullduggery to a fine art. They were experts at extricating the crabs and would eat only their fleshy abdomens and discard the rest. Mind you, that was only a few individuals out of a great many Hippocampines, but I could never keep hermit crabs in the same tank with those specific seahorses.

It’s the smallest hermit crabs that are at greatest risk, of course, but this behavior sometimes becomes habitual. So if my experience is any guide, crab killing could become a bad habit for the seahorse that is doing the stalking and you’ll have to watch that particular pony around hermit crabs from now on. Once they have discovered how to go about it, a seahorse may develop a taste for hermit hinders and consider them to be a regular part of its menu henceforth.

On the other hand, sometimes it’s the micro-hermits that are the troublemakers. I have seen a few cases in which individual hermits have developed a bad habit of harassing the seahorses. Like the rare seahorses that occasionally develop a taste for hermit hind-ends, there are microhermit crabs that on rare occasions will bother the ponies, often by latching onto their tails. This most often occurs when the seahorses and hermits are attracted to the feeding tray at mealtime and brought into close proximity, and it is usually just an isolated incident. Oftentimes this can be prevented simply by elevating the feeding station, which puts it out of reach of the pesky hermits. But just occasionally, a microhermit makes himself a serious persistent pest, and these unusually boisterous individuals should be weeded out of your cleanup crew immediately.

Likewise, most of the time, microhermit crabs coexist perfectly well with their fellow janitors in the cleanup crew. But I’ve had more than a few tiny hermits with a taste for escargot that persecuted snails mercilessly. These cold-blooded little assassins would kill the snails in order to appropriate their shells. Once they had dined on the former occupant, they would take up residence in their victim’s cleaned-out shell! It soon became clear that these killer crabs were driven not by hunger, but by the need for a new domicile. Once I realized they were house-hunting, I found I could curb their depredations but providing an assortment of small, empty seashells for the hermits to use. Colorful Nerite shells are ideal for this. However, sometimes the bad behavior persists and the offending individual has to be relocated.
<Close quote>

In your case, Kaitlyn, since the microhermits were murderous little hellions in your dwarf tank, it would be a very good idea to avoid even the smallest hermit crabs in your dwarf set up in the future, as I am sure you are doing.

Those are my thoughts regarding tank mates for dwarf seahorses, Kaitlyn. I should think you would have no trouble at all including colorful feather dusters, fromia sea stars, and a Lettuce Nudibranch in your dwarf tank. But I would avoid all microhermit crabs and as long as the Cerith snails and amphipods are doing a good job as scavengers, then avoid the Nassarius snails as well, unless you can make certain that you can obtain the genuine Nassarius vibex.

Best of luck with your dwarf tank and the macroalgae you are cultivating!

Pete Giwojna

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