Re:Stocking 40 Gallon Tank

Dear Kyme:

Okay, that sounds good! If your live rock is loaded with copepods and amphipods, and your Mandarin goby is already accepting frozen Mysis well, then the chances are good that the Mandarin will do well in your tank. And he certainly will make a splendid tankmate for your seahorses.

Yes, I think it would be very prudent if you return the juvenile Hippocampus kelloggi. Unfortunately, nobody is having any luck keeping the little H. kelloggi that are coming into the country nowadays for the reasons we discussed in my previous post. The seahorses simply would not have lasted long in a warm water aquariums with live corals…

If you’re going to remove the sand sifting starfish, Kyme, then I would recommend replacing it with one or more of the colorful little Fromia sea stars instead. 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 yours 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, making them a useful addition to the cleanup crew for a seahorse tank.

You might also consider diversifying your snail assortment somewhat, Kyme. This is normally what I advise the home hobbyist regarding the cleanup crew for a seahorse tank:

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 diatoms, but will consume red slime 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, 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, 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 curb their depredations but 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 it 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, that’s the quick rundown on seahorse-safe sanitation engineers, Kyme.

The only other thing I would suggest is to please consider participating in the free Ocean Rider training program for seahorse keepers before you purchase Mustangs or Sunbursts to replace the H. kelloggi seahorses. It’s a correspondence course that’s conducted entirely via e-mail, and if you would like to give it a try, just contact me ([email protected]) off list with your first and last name and I will get you started on the first lesson immediately.

Best wishes with all your fishes, Kyme!

Happy Trails!
Pete Giwojna