question for advanced seahorsemen

Dear JulieAnn:

This is normally what I advise home hobbyists regarding compatible tankmates for Mustangs and Sunbursts (Hippocampus erectus):

Tropical Tankmates

I have prepared a list of suitable fishes and invertebrates that generally make compatible tankmates for tropical seahorses below. Avoid fin nippers and aggressive, territorial fish that would be inclined to bully or physically abuse the seahorses, such as damsels, most clownfish, triggerfish, angels, puffers, cowfish and the like, as well as any predatory fishes that are large enough to swallow a seahorses, such as lionfish, anglers, sargassumfish, rays, large groupers, and morays. For best results, other fishes that would not persecute the seahorses in any way should also generally be excluded because they are active, aggressive feeders that would out-compete the seahorses for food. This includes most butterflyfish, tangs, and wrasse. Stinging animals like anemones and jellyfish are unsuitable, as are other predatory invertebrates such as lobsters, mantis shrimp, certain starfish, and most crabs.

Clownfish meet many of the criteria for suitable tankmates, but should generally be regarded with caution (Giwojna, Feb. 2004). Most species, such as Tomato Clowns (Amphiprion frenatus), Maroon Clowns (Premnas biaculeatus), and Skunk Clownfish are surprisingly aggressive and territorial, and should be shunned on that basis. Others do best when keep with anemones, which are a threat to seahorses. All clownfish are prone to Brooklynella and Marine Velvet (Amyloodinium), and should be considered Ich (Cryptocaryon irritans) magnets as well (Giwojna, Feb. 2004). The only species I would recommend as companions for seahorses are Percula Clowns (Amphiprion percula) and False Percula Clownfish (A. ocellaris), and then only after a rigorous quarantine period (Giwojna, Feb. 2004). Captive-bred specimens are best and the cultured A. occelaris or percula are not normally territorial or aggressive toward seahorses.

In short, fishes that are suitable as companions for seahorses must be docile, nonaggressive specimens, which are fairly deliberate feeders that won’t out-compete them for food. Some good candidates include:

Anthias (assorted Mirolabrichthys, Pseudanthias, and Anthias sp.)
Firefish Goby (Nemateleotris magnifica)
Purple Firefish Goby (Nemateleotris decora)
Gobies (assorted small species)
Neon Goby (Gobiosoma oceanops)
Assessors (Assessor spp.)
Midas Blenny (Ecsenius midas)
High Hats (Equetus acuminatus)
Marine Betta (Calloplesiops altivelis)
Banggai or Banner cardinals (Pterapogon kauderni)
Pajama cardinals (Apogon nematoptera)
Pipefishes (assorted small species)
Percula clownfish (Amphiprion percula)
False percula clownfish (Amphiprion ocellaris)
Royal Grammas (Gramma loreto)
Blackcap Basslets (Gramma melacara)
Green Chromis (Chromis viridis)
Blue Reef Chromis (Chromis cyaneus)
Longnose Hawkfish (Oxycirrhites typus)
Six Line Wrasse (Psuedocheilinus hexataenia)
Flasher Wrasse (Paracheilinus sp.)
Fairy Wrasse (Cirrhilabrus spp.)
Scooter Blennies (Synchiropus spp.)
Green Mandarin Goby or Dragonet (Pterosynchiropus splendidus)
Psychedelic Mandarin Goby or Dragonet (Pterosynchiropus picturatus)
Orchid Dottyback (Pseudochromis fridmani) – avoid other Pseudochromis species!

Mandarin gobies or dragonets (Pterosynchiropus spp.) are peaceful, deliberate feeders with brilliant colors that do well with seahorses and often even learn to accept frozen Mysis in time. But they are best reserved for very large, well-established aquaria with lots of live rock that supports an adequate population of copepods and amphipods to sustain them.

Good inverts for seahorses include decorative cleaner shrimp like those listed below:

Peppermint Shrimp (Lysmata wurdemanni)
Scarlet Cleaner Shrimp or Skunk Cleaner Shrimp (Lysmata amboinensis)
Fire Shrimp (Lysmata debelius)
Harlequin Shrimp (Hymenocerus elegans and H. picta) — predatory on sea stars;
and/or
large ornamental snails (living sea shells) such as the following:
Tiger Cowry (Cypraea tigris)
Deer Cowry (Cypraea cervus)
and/or
Assorted Feather Dusters (Sabellastatre magnifica, Sabella sp.) whose colorful crowns resemble gaily-colored parasols.

As far as starfish go, it’s best to avoid a large predatory species such as chocolate chip starfish and African starfish (Protoreaster spp.). I would describe predatory sea stars such as these as "opportunistic omnivores," meaning that they are likely to eat any sessile or slow-moving animals that they can catch or overpower. For instance, I would not trust them with snails, clams, tunicates, soft corals and the like. Most fishes are far too fast and agile to be threatened by sea stars, but seahorses are sometimes an exception due to their sedentary lifestyle and habit of perching in one place for extended periods of time. What occasionally happens, in the confines of the aquarium, is that a predatory starfish may pin down the tail of a seahorse that was perched to the piece of coral or rock the starfish was climbing on, evert its stomach, and begin to digest that portion of the seahorse’s tail that is pinned beneath its body. That’s a real risk with large predatory species such as the beautiful Protoreaster starfish, which are surprisingly voracious and aggressive for an echinoderm.

But there are a number of colorful starfish that do well with seahorses. Any of the brightly colored Fromia or Linkia species would make good tankmates for seahorses. However, bear in mind that, like all echinoderms, starfish are very sensitive to water quality and generally will not do well in a newly established aquarium. Wait until your seahorse tank is well-established and has had a chance to mature and stabilize before you try any starfish.

Three attractive species I can recommend are the Fromia Sea Star or Marbled Sea Star (Fromia monilis), the Red Bali Starfish (Fromia milliporella), and the Red Starfish (Fromia elegans), which are all perfectly safe to keep with seahorses. They are not nearly as delicate as the Linkia species and should do well in the tank such as you’re planning that has lots of live rock and optimum water quality, and are nonaggressive starfish that feed primarily on detritus and meiofauna on live rock and sandy substrates.

As for aquarium janitors that will do well with Sunbursts, JulieAnn, this is what I typically recommend with regard to aquarium cleaners:

Sanitation Engineers: The Cleanup Crew

Once the tank has cycled, it’s a good idea to begin stocking your system by adding the cleanup crew first. Assorted snails and micro hermit crabs form the backbone of the cleanup crew in most seahorse tanks, but the proportion of snails to hermits is a matter of personal preference. Many hobbyists favor using nothing but a variety of snails, others favor a 50/50 mix of snails and hermits, while others like to use a preponderance of snails with just a few hermits. Personally, I prefer a cleanup crew consisting of a mixture of assorted snails and micro hermits (heavy on the snails but very light on hermits) at a density of no more than 1-2 janitors per gallon at the most. But if you are new to seahorse keeping, the safest plan may be to go with aquarium janitors that are 100% snails of various types, which will eliminate any possible mischief the hermit crabs may otherwise get into from the equation.

The snail assortment may include bumble bee snails, Trochus snails, margaritas, Astrea and Cerith snails, red foot Moon snails, etc., but especially 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. They do a good job of cleaning up meatier leftovers such as uneaten Mysis and can fill the role played by microhermit crabs for hobbyists who prefer a cleanup crew consisting only of snails.

A varied assortment of snails is very desirable because different types of snails have different habits, seek out various microhabitats within the aquarium, and prefer to eat different things. Some are herbivores that feed on microalgae, and some of the herbivorous snails prefer to graze on it from the substrate, others like to clean it from the rocks, and still others love to scrape algae off the aquarium glass. Furthermore, the different herbivorous snails tend to specialize on different types of microalgae and have definite preferences as to the types of algae they will eat, so it’s important to have a nice variety of snails that cover all the bases in that regard. It’s equally important to include some omnivorous snails in your assortment, which will go after meaty leftovers, along with the vegetarians. And you’ll want to have plenty of detritivores, too, which will feed on detritus and decaying organic matter in the aquarium.

For best results, Astrea sp. snails should go in the tank as soon as the ammonia and nitrite levels are down to zero in order to keep nuisance algae from gaining a foothold in your tank. Introduced as soon as possible to a new aquarium, that has reached this cycling phase, Astrea snails effectively limit the development of all microalgae. In other words, they are good at eating brown diatoms, but will consume red slime algae and green algae as well.

Astrea snails can be identified by their sharp conical shell with pronounced ridges spiraling down the shell. Like many of the Turbo and Trochus snails to which they are related, Astrea snails are notorious for being unable to right themselves once they are upended. The diligent aquarist should be aware of this and quickly right any of the snails that have become dislodged and landed upside down in order to prevent their premature demise.

But you must avoid predatory snails such as tulip snails, whelks, horse conchs, crown snails (Melanogena corona), and the venomous cone snails (Conus spp.), which can kill a human with a single sting from their harpoon like radula. Tulip snails, horse conchs, whelks, and crown conchs will hunt down and eat the other snails in your cleanup crew, whereas cone snails prey on small fishes in addition to presenting a deadly hazard to the aquarist.

For hobbyists who like to include small hermit crabs as part of their cleanup crew, I like a combination of Dwarf Blue-leg (Clibanarius tricolor), Left-handed (Calcinus laevimanus), Mexican Red Legged Hermits (Clibanarius digueti) and above all, Scarlet Reef hermit crabs (Paguristes cadenati), which are my personal favorites. It’s very important to obtain dwarf or microhermit crabs for a seahorse tank — species that start out small and remain small even when they reach their maximum size, such as the species mentioned above.

The Scarlet Reef Hermit Crab (Paguristes cadenati) is a colorful micro-hermit that’s a harmless herbivore. So cannibalism isn’t a concern at all for these fellows, nor are they likely to develop a taste for escargot. As hermits go, most of the time the Scarlet Reefs are perfect little gentleman and attractive to boot. Best of all, they eat all kinds of algae, including nuisance algae such as red, green and brown slimes, as well as green hair algae.

If you’re going to have any hermits, stick with species like the above, which are known as micro hermits because they start out tiny and stay small. Avoid Anomura species of hermit crabs no matter how small they are, however, because they will kill Astraea snails to obtain their shells.

A mixture of the snails and micro hermits we have discussed will provide a very good balance of herbivores, omnivores, and detritivores that are all active scavengers and completely compatible with seahorses. They will clean up meatier leftovers such as frozen Mysis as well as helping to control nuisance algae.

With regard to the hermit crabs, there are a couple of other possible risks you should be aware of aside from the possibilities that the hermits could grow a large enough to be a threat to the seahorses.

For example, sometimes it works the other way around. Micro-hermit 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.

On the other hand, sometimes it’s the micro-hermits that are the troublemakers. Most of the time, they 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 sometimes curb their depredations by providing an assortment of small, empty seashells for the hermits to use. Colorful Nerite shells are ideal for this.

Because of these potential problems with the microhermit crabs, many seahorse keepers prefer to avoid the hermits altogether and compile a group of sanitation engineers and aquarium scavengers that consists entirely of assorted snails instead. That’s probably the simplest and safest option if this will be the first time you have assembled a cleanup crew for a seahorse tank.

After the tank has been up and running for several months, you can add a few large Peppermint Shrimp (Lysmata wurdemanni) and/or Scarlet Cleaner Shrimp or Skunk Cleaner Shrimp (Lysmata amboinensis) or Fire Cleaner Shrimp (Lysmata debelius) to complete your cleanup crew and add a touch of color and activity to the tank.

Peppermint shrimp (Lysmata wurdemanni) are a favorite with seahorse keepers because they eat Aiptasia rock anemones, and both the peppermints and Scarlet cleaner shrimp (Lysmata amboinensis) will perform another useful service by grooming the seahorses and cleaning them of ectoparasites. As an added bonus, they reproduce regularly in the aquarium, producing swarms of larval nauplii that the seahorses love to eat.

Just remember, it is important to select good sized cleaner shrimp for your seahorse tank(s). Seahorses will actively hunt small cleaner shrimp and they are quite capable of killing shrimp that are far too big to swallow whole, so the cleaners need to be large enough that they are not regarded as potential prey.

Another thing to keep in mind when introducing cleaner shrimp to your aquarium is that they are more sensitive to water quality and rapid changes in pH, temperature, or salinity than fishes are, meaning the shrimp need to be acclimated more carefully and gradually. Whereas drip acclimation should be avoided for seahorses that have been on the shipping bag for 24 hours or more, it is the perfect way to acclimate delicate shrimp from your LFS. They will do best if drip acclimated to the new aquarium over a period of several hours to allow them to adjust to any differences in the water parameters very gradually.

Shrimp that are introduced to a new aquarium too abruptly will not flourish and are liable to die within a day or two from the stress of acclimation, unable to adjust to any significant differences in pH or salinity, or they simply fail to thrive and expire a week or two later for no apparent reason. If the shock is too great, they will autotomize, dropping legs, claws and/or antennae immediately upon being introduced to the new aquarium conditions.

Okay, JulieAnn, that’s the quick rundown on compatible tank mates and suitable sanitation engineers for Sunbursts.

Since you are new to seahorses, JulieAnn, I would also like to invite you to participate in the Ocean Rider seahorse training program. It is a correspondence course conducted entirely via e-mail that is completely free of charge and discusses everything you need to know about setting up a new seahorse tank and optimizing it for seahorses, as well as comprehensive information on the care and keeping of seahorses, including feeding, compatible tank mates, courtship and breeding, raising the babies, and disease prevention and control. (For complete details on the seahorse training program, see the pinned discussion thread at the top of this forum.)

One of the lessons in the training program is devoted entirely to a thorough discussion of compatible tank mates for Mustangs and Sunbursts. There are a total of 10 lessons, all of which are loaded with useful tips and helpful suggestions for the seahorse keeper. In short, the training program discusses setting up for seahorses and maintaining your seahorses in much more detail then we can go into on a simple discussion forum like this.

If you would like to give the seahorse training program a try, JulieAnn, just contact me off list ([email protected]) with a brief message that includes your full name (first and last) and I will get you started out with the first lesson right away. Once we begin corresponding, I will continue to work with you personally until your new aquarium is up and running, ready to receive the seahorses.

Best wishes with all your fishes, JulieAnn!

Happy Trails!
Pete Giwojna