Re:We need help

Pete Giwojna

Dear hobbyist:

I’m sorry to hear about the difficulties you have been having with your new 10-gallon aquarium. The lack of stability and poor water quality indicate that the biological filtration in the tank is simply being overwhelmed at this point and cannot keep up with the wastes produced by the seahorses, which are messy feeders. This problem is being exacerbated by the fact that your sponges have died and are further degrading your water quality.

The first thing you need to do is to very carefully remove the sponges from the aquarium and then perform a major water change immediately. Be prepared to replace all 10 gallons of water after you extricate the sponges.

The reason you must proceed with great caution removing the sponges is because they may contain toxic substances within their fibrous bodies that could be released into the aquarium if the sponges break up or disintegrate while you are handling them. So take great care to remove the sponges complete and intact, if possible.

As soon as the sponges have been removed, replaced as much of the water in your aquarium with freshly mixed saltwater that you have preadjusted to the same temperature, pH, and specific gravity as the aquarium, and add some high-quality activated carbon to the filter on the aquarium. This will prevent any toxins that may have been leached into the water from the moribund sponges from causing harm. Filtration with activated carbon will effectively remove most organic toxins and will be very helpful in this case. Polyfilter pads may also useful in such a situation.

I would carefully remove and discard the sponges, add some heavy activated carbon filtration to your aquarium, and perform a series of water changes. Replace the activated carbon with fresh carbon after several days to remove the toxins and pollutants the old carbon has absorbed, and you should notice an improvement in your water quality.

Do not attempt to replace the dead sponges with new colorful sponges. It is going to be very difficult to keep sponges alive in a 10-gallon aquarium and I would abandon that project, which is very likely doomed to failure under the circumstances. Live sponges are best reserved for well-established reef systems.

Yes, if your seahorse tank is being overrun with anemones you definitely need to remove them. Since they have been proliferating so rapidly, it’s almost certain that they are Aiptasia rock anemones, in which case you cannot simply uproot the anemones and physically remove them from the tank. These particular anemones can reproduce by budding or fragmentation, and attempts to detach them from the substrate will often leave portions of the disc behind which can develop into new anemones.

A few isolated Aiptasia rock anemones won’t pose a serious threat to any of the larger seahorses such as Mustangs and Sunbursts (Hippocampus erectus) since the ponies will be careful to avoid them. However, as you have discovered, Aiptasia rock anemones can rapidly increase in number and become a threat to seahorses when they are so numerous it is difficult for the seahorses to avoid coming in contact with them. It sounds like that’s the situation you are now dealing with since the anemones are getting out of control in your small 10-gallon tank. The danger is not that the Aiptasia will capture and consume a small seahorse, but rather that their stinging cells or nematocysts can penetrate the integument of the seahorse and leave it vulnerable to secondary infections. For this reason, I would strongly suggest that you take measures to deforest the orchards of Aiptasia that have sprung up on your live rock.

Aiptasia rock anemones can easily be killed by injecting them with a number of solutions — Kalkwasser, boiling water, lemon juice, a number of commercial products (e.g., Joe’s Juice) — and in a severe case like yours, I suggest using a combination of such injections and biological control to eradicate them.

Peppermint Shrimp (Lysmata wurdemanni) will do a fine job of controlling Aiptasia rock anemones and they do great with seahorses. They are popular additions to a seahorse tank because hobbyists like to use them to augment their cleanup crews and add a splash of color and activity to their tanks. Aside from their utility as attractive scavengers, they often perform a useful service by grooming the seahorses, which is fascinating to watch, and regularly reproduce, releasing swarms of nauplii many seahorses love to eat. Peppermint Shrimp are especially popular because they are natural predators of Aiptasia rock anemones and do a wonderful job of eradicating these pests from the aquarium.

One rule to keep in mind when buying your Peppermints is to select the largest possible 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. Add a few good-sized peppermint shrimp to the seahorse enclosure and they will happily clean up all of the smaller Aiptasia rock anemones.

If you pitch in by periodically injecting the largest Aiptasia, you will soon whittle down that forest of rock anemones. As the number of Aiptasia are reduced, they will become easier and easier to eliminate. There will be fewer of the large anemones for you to inject and the peppermint shrimp will eventually work their way through all of the smaller ones.

Eliminating the dead sponges and Aiptasia rock anemones will help you start to get things back on track, but you’re also going to need to be careful to feed your seahorses properly in a small tank like yours with no margin for error. This means target feeding your seahorses or training them to eat from a feeding station, as explained below:

Feeding Seahorses

When keeping seahorses in an appropriately elaborate environment, it is imperative that you feed them properly! Domesticated seahorses thrive on enriched frozen Mysis as their staple, everyday diet. But the worst thing you can do when feeding the seahorses in a intricate reef or live rock environment is to scatter a handful of frozen Mysis throughout the tank to be dispersed by the currents and hope that the hungry horses can track it all down. Inevitably some of the frozen food will be swept away and lodge in isolated nooks and crannies where the seahorses cannot get it (Giwojna, 2005). There it will begin to decompose and degrade the water quality, which is why ammonia spikes are common after a heavy feeding. Or it may be wafted out into the open again later on and eaten after it has begun to spoil. Either outcome can have dire consequences (Giwojna, 2005).

The best way to avoid such problems is to target feed your seahorses or set up a feeding station for them. See my online article in Conscientious Aquarist for a detailed discussion explaining exactly how to set up a feeding station and train your seahorses to use it:

Click here: Seahorse Feeders

Personally, I prefer to target feed my seahorses instead. The individual personalities of seahorses naturally extend to their feeding habits. Some are aggressive feeders that will boldly snatch food from your fingers, while some are shy and secretive, feeding only when they think they’re not being observed. Some like to slurp up Mysis while it’s swirling through the water column, and some will only take Mysis off the bottom of the tank. Some are voracious pigs that greedily scarf up everything in sight, and some are slow, deliberate feeders that painstakingly examine every morsel of Mysis before they accept or reject it. Some eat like horses and some eat like birds. So how does the seahorse keeper make sure all his charges are getting enough to eat at mealtime? How does the hobbyist keep the aggressive eaters from gobbling up all the mouth-watering Mysis before the slower feeders get their fair share? And how can you keep active fishes and inverts with seahorses without the faster fishes gobbling up all the goodies before the slowpoke seahorses can grab a mouthful (Giwojna, unpublished)?

Target feeding is the answer. Target feeding just means offering a single piece of Mysis to one particular seahorse, and then watching to see whether or not the ‘horse you targeted actually eats the shrimp. Feeding each of your seahorses in turn that way makes it easy to keep track of exactly how much each of your specimens is eating (Giwojna, unpublished).

There are many different ways to target feed seahorses. Most methods involve using a long utensil of some sort to wave the Mysis temptingly in front of the chosen seahorse; once you’re sure this has attracted his interest, the Mysis is released so it drifts down enticingly right before the seahorse’s snout. Most of the time, the seahorse will snatch it up as it drifts by or snap it up as soon as it hits the bottom (Giwojna, unpublished).

A great number of utensils work well for target feeding. I’ve seen hobbyists use everything from chopsticks to extra long tweezers and hemostats or forceps to homemade pipettes fashioned from a length of rigid plastic tubing. As for myself, I prefer handfeeding when I target feed a particular seahorse (Giwojna, unpublished).

But no doubt the all-time favorite implement for target feeding seahorses is the old-fashioned turkey baster. The old-fashioned ones with the glass barrels work best because the seahorses can see the Mysis inside the baster all the way as it moves down the barrel and out the tip. By exerting just the right amount of pressure on the bulb, great precision is possible when target feeding with a turkey baster. By squeezing and releasing the bulb ever so slightly, a skillful target feeder can keep a piece of Mysis dancing at the very tip of the baster indefinitely, and hold the tempting morsel right in front of the seahorse’s mouth as long as necessary. Or if the seahorse rejects the Mysis the first time it drifts by, a baster makes it easy to deftly suck up the shrimp from the bottom so it can be offered to the target again. In the same way, the baster makes it a simple matter to clean any remaining leftovers after a feeding session (Giwojna, unpublished). (You’ll quickly discover the feeding tube is also indispensable for tapping away pesky fish and invertebrates that threaten to steal the tempting tidbit before an indecisive seahorse can snatch it up.)

In short, target feeding allows the hobbyist to assure that each of his seahorses gets enough to eat without overfeeding or underfeeding the tank. And it makes it possible to keep seahorses in a community tank with more active fishes that would ordinarily out-compete them for food, since the aquarist can personally deliver each mouthful to the seahorses while keeping more aggressive specimens at bay (Giwojna, unpublished).

The key to keeping active specimens like cleaner shrimp successfully with seahorses is to feed the other fish and inverts with standard, off-the-shelf aquarium foods first, and once they’ve had their fill, then target feed the seahorses (Giwojna, unpublished).

In short, feeding your seahorses properly and removing the dead sponges will help your tank to stabilize and improve the water quality, but I really think that you are fighting a losing battle attempting to keep a pair of large seahorses like Sunbursts in an aquarium that is so small. For one thing, they will not be able to mate successfully in a 10-gallon aquarium, and the lack of water depth in such a shallow tank will leave them susceptible to problems with gas bubble syndrome, a potentially fatal condition. And the water quality can go downhill so quickly in such a small volume of water that you will find it very difficult to maintain the water chemistry and aquarium parameters where you want them.

The smallest aquarium I would recommend for a pair of Mustangs or Sunbursts (H. erectus) would be a 20-gallon Extra-High All Glass Aquarium and the 30-gallon Extra-High would be much preferable. In general, if you’re new to seahorses, you will be better off starting out with the largest aquarium you can reasonably afford and maintain (the taller, the better). In general, a tank of at least 40 gallons (150 L) is best since that’s the size when one begins to see significant benefits in terms of the greater stability a larger volume of water can provide. An aquarium of 40-gallons or more will be more resistant to overcrowding and to rapid fluctuations in temperature, pH, and salinity than smaller setups. The larger the aquarium the larger the margin for error it offers the aquarist and the greater the benefits it provides in terms of stability.

It is equally desirable to select an aquarium at least 20-inches high when keeping the greater seahorses. They need the vertical swimming space to perform their complex mating ritual and successfully complete the egg transfer, which is accomplished while the pair is rising through the water column or drifting slowly downwards from the apex of their rise. If the aquarium is too shallow, eggs will be spilled during the transfer from the female to the male’s brood pouch, and mating becomes increasingly difficult or impossible below a certain minimum depth. A tall aquarium can also help protect the seahorses from depth-related health problems such as bloated pouch and certain forms of gas bubble syndrome.

So for best results you may want to consider upgrading your seahorse tank to a larger unit. Let me know if that is something you are willing to consider and I would be happy to explain the best way to go about it. A 20- or 30-gallon Extra-High All Glass Aquarium can be set up quite economically and would make a much better home for your pair of Sunbursts.

If you do upgrade your seahorse tank, then I would suggest converting your 10-gallon setup to an invertebrate tank instead. Choose out one or two pieces of colorful live rock with a good growth of coraline algae to give the 10 gallon better stability and then add some feather dusters or tubeworms, a few small hermit crabs and a small starfish or two (once the tank has stabilized), an interesting arrow crab (Stenorhynchus seticornis) and/or a decorator crab, and some decorative shrimp (perhaps a pair of coral banded shrimp, Stenopus hispidus, or Scarlet cleaner shrimp, Lysmata amboinensis). You’ll want to add some assorted snails as well to control nuisance algae and add a little more interest to the tank.

Your Sunbursts will be much happier and healthier in a larger, taller aquarium, and an interesting selection of invertebrates will be far more trouble free in your 10-gallon tank. You could also add a couple of small gobies (e.g., any goby, a clown goby, or a red head goby) to the 10-gallon invertebrate setup.

Best of luck removing a dead sponges and rock anemones and stabilizing your 10-gallon aquarium!

Pete Giwojna

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