Dwarfs tank questions

Dear Donna:

I can make a few suggestions that should help improve your success with the dwarf seahorses (Hippocampus zosterae).

First of all, I would suggest using decapsulated brine shrimp cysts when you hatch out the Artemia. That will cut down on much of the “gunk,” which is largely due to the inedible egg shells that the brine shrimp hatch out of, Donna. In addition, the brine shrimp or Artemia that you hatch out of the decapsulated cysts are more nutritious. They have not had to expend any energy or resources hatching out of the tough egg shells, so they will provide better nutrition.

Secondly, I would recommend adding some Americamysis bahia (Mysidopsis bahia) to your dwarf seahorse setup and fry tanks. They work great as a clean-up crew and when the ponies get large enough, they can feed on the mysids.

Thirdly, if you’re using live sand and live rock in your dwarf tank, I recommend adding a dose of fenbendazole (brand name Panacur) to prevent hydroids from causing trouble.

As you know, outbreaks of hydroids, which are the bane of all dwarf seahorse keepers, are pretty much inevitable otherwise. Sooner or later, they appear in all unprotected dwarf seahorse tanks, and they have wiped out more dwarf tanks that all of the other factors combined together.

Fortunately, I know how you can overcome the issue with hydroids and easily prevent them from getting a foothold in your dwarf seahorse tank, and I would be happy to explain how you can do exactly that, Donna.

In a nutshell, many hobbyists nowadays are finding that the best system for keeping dwarf seahorses (Hippocampus zosterae) is to set up a small tank with live rock and live sand, and then pretreat the tank with fenbendazole (brand name Panacur). The regimen of fenbendazole will destroy any hydroids, Aiptasia rock anemones, or bristleworms that may be present in the live rock or live sand, and residual amounts of the medication will gradually leach out of the porous live rock for months afterward, providing long-term protection from these pests. Repeating a dose of fenbendazole two or three times a year — say every 3-6 months — as a precaution thereafter will maintain the protective affects indefinitely…

If used at the recommended dosages, the fenbendazole is not harmful to dwarf seahorses or their babies, and it does not normally have any effect on copepods or amphipods, so you should be able to maintain a thriving pod population in such a tank.

Regarding the dwarf seahorses (H. zosterae), Donna, there have been some very helpful developments with regard to controlling hydroids, which are of course the great scourge of dwarf seahorse keepers. The latest trend nowadays is to keep live rock and live sand that have been treated with fenbendazole (brand name Panacur) in the dwarf setups to eradicate hydroids and other unwanted pests. That allows the dwarf seahorses to benefit from the biological filtration and stability provided by the LR and LS, while at the same time safely providing long-term control for hydroids, Aiptasia rock anemones, and bristleworms.

As you know, Donna, in the past dwarf seahorse keepers would normally avoid live rock and live sand like the plague in order to reduce the risk of hydroids getting started in their aquarium, but there are ways around that have actually turned the live rock into an advantage for preventing hydroids, as we’ll discuss in more detail below.

Live rock and live sand are excellent for supplemental filtration and adding stability to a dwarf seahorse tank, but it also means that hobbyists are going to have chronic problems with hydroids and Aiptasia rock anemones unless they take special precautions to control them, which is surprisingly easy to accomplish.

Sooner or later hydroids will appear in any marine aquarium that is receiving regular feedings of rotifers, copepods, or baby brine shrimp. It’s inevitable because they can gain entry into the aquarium in many ways. For example, they are notorious hitchhikers. Both the colonial polyp stage and the free-swimming micro-jellies can thumb a ride on live rock, macroalgae, hitching posts, sand or gravel, specimens of all kinds, or within so much as a single drop of natural seawater (Abbott, 2003). Beware of fuzzy looking seashells! Very often hydrozoans come in on the shells of the hermit crabs or snails we purchase as aquarium janitors (Abbott, 2003). Or they may be introduced with live foods, or even among Artemia cysts, in some cases it seems. They can even be transferred from tank to tank in the aerosol mist arising from an airstone or the bubble stream of a protein skimmer.

So with the live rock and live sand, aquarists are going to have an ongoing problem with hydroids and likely also Aiptasia rock anemones in their dwarf setups, and that’s ordinarily a cause for great concern. Because of their diminutive dimensions, dwarf seahorses are susceptible to the stings from hydroids and Aiptasia rock anemones. Hydroids in particular are especially problematic for dwarves because once they find their way into a dwarf seahorse setup or nursery tank, the dreaded droids can explode to plague proportions very quickly because conditions are ideal for their growth: perfect temperatures, an abundance of planktonic prey that is renewed every few hours, and a complete absence of predators. As they proliferate and spread, they will soon begin to take a toll on the seahorse fry and even adult dwarfs can succumb to multiple stings or secondary infections that can set in at the site of a sting (Abbott, 2003).

But there is a way you can turn this situation to your advantage and eliminate the risk of hydroids, Aiptasia rock anemones, and bristleworms from a dwarf seahorse tank, Donna. Treating a dwarf tank with a regimen of fenbendazole will eradicate these pests and provide long-lasting protection from hydroids and Aiptasia for your dwarf seahorses. Allow me to explain.

Eliminating Hydroids

Hydroids can be controlled in the aquarium by using a medication known as fenbendazole to treat the tank over a period of days. Fenbendazole (brand name Panacur) is an inexpensive anthelmintic agent (dewormer) used for large animals such as horses, and the de-worming granules can be obtained without a prescription from stores that carry agricultural products (e.g., farm and ranch equipment, farming supplies and products, veterinary supplies, livestock and horse supplies, livestock and horse feed). If you live in a rural area, those would be good places to obtain it as well.

However, there are a couple of things you should keep in mind when treating an aquarium with fenbendazole. Administering a regimen of fenbendazole (FBZ) or Panacur will eradicate any hydroids, Aiptasia rock anemones, or bristleworms from live rock or live sand, thereby rendering them completely seahorse safe. The recommended dose is 1/8 teaspoon of the horse dewormer granules (22.2% fenbendazole) per 10 gallons of water. Dose aquarium with 1/8 teaspoon/10 gallons every other day until you have administered a total of 3 such treatments (Liisa Coit, pers. com.). Even one dose will do a fine job of eradicating bristeworms, but Aiptasia rock anemones and hydroids are a bit tougher and may require 2-3 doses to eliminate entirely.

Because fenbendazole is essentially a de-worming agent, it will destroy any bristleworms, flat worms, spaghetti worms or the like. Fenbendazole does not have any adverse effects on biological filtration, but be aware that it is death to many Cnidarians besides hydroids. Mushrooms and related corals are generally not affected, but expect it to have dire effects on other corals (e.g., sinularias), polyps, gorgonians, and anemones. In general, any Cnidarians with polyps that resemble the stalked family of Hydrozoans are likely to be hit hard by fenbendazole, so don’t use this treatment in a reef tank! Dwarf seahorse keepers, of course, don’t keep alive corals so this is not a disadvantage for a dwarf seahorse tank at all.

Also be aware that fenbendazole seems to soak into the porous live rock and be absorbed indefinitely. I know one hobbyist who transferred a small piece of live rock that had been treated with fenbendazole (Panacur) months earlier into a reef tank, where it killed the resident starfish and Astrea snails. So enough of the medication may be retained within treated live rock to impact sensitive animals months after the fenbendazole was administered. Don’t treat live rock intended for reef systems with fenbendazole (Panacur)! On the other hand, however, this makes live rock that’s been pretreated with fenbendazole very useful for providing long-term hydroid protection for dwarf seahorse keepers.

At the lower dosage recommended for nursery tanks and dwarf seahorse tanks with fry (1/16 tsp. per 10 gallons), fenbendazole normally does not harm cleaner shrimp and decorative shrimp. With the exception of Astrids (Astrea), Coit and Worden have found it does not usually affect the types of snails typically used as cleanup crews (e.g., Nassarius, Ceriths, and Nerites). It will kill starfish but copepods, hermit crabs, and shrimp are normally not affected.

Macroalgae such as the feathery or long-bladed varieties of Caulerpa or Hawaiian Ogo (Gracilaria) are not harmed by exposure to fenbendazole at even triple the normal dose. In fact, if you will be using Caulerpa in your nursery tanks to provide hitching posts for the fry and serve as a form of natural filtration, it’s a very wise precaution indeed to treat them with a regimen of fenbendazole beforehand.

So fenbendazole (FBZ) or Panacur is primarily useful for ridding bare-bottomed nursery tanks and dwarf seahorses setups of hyrdroids and Aiptasia anemones, ridding Caulerpa and other macroalge of hydroids or Aiptasia before its goes into the aquarium, and cleansing live rock of bristleworms, hydroids, and Aiptasia rock anemones before it is introduced to the aquarium.

It can also be used to eradicate bristleworms, hydroids, an Aiptasia from an established aquarium if it does not house sensitive animals such as live corals and gorgonians, starfish, Astrea snails, or tubeworms and other desirable worms that may be harmed by FBZ, providing you monitor the ammonia levels closely and are prepared to deal with the ammonia spike that may result from the sudden death of the worm population.

Live rock and live sand that has been pretreated with fenbendazole are quite safe for dwarf seahorses and their fry, and because the medication soaks into the porous interior of the live rock and then is gradually released again, it can provide a dwarf seahorse tank with long-lasting protection against stinging organisms like hydroids and Aiptasia rock anemones. The amount of the fenbendazole that gradually leaches out of the porous live rock is quite miniscule. It is effective in controlling hydroids and various marine worms even in the insignificant dosage that seeps out of the treated LR because they are sensitive to the medication and even though the dose of fenbendazole that is released is negligible, it is being released at a fairly constant rate and therefore maintaining a continuous, very low level of fenbendazole in the tank. Fenbendazole is an anthelminthic agent or dewormer, designed to kill certain invertebrates such as worms, and it is therefore deadly to bristleworms and cnidarians with nematocysts such as Aiptasia anemones and hydroids, but it is quite safe to use with vertebrates such as seahorses at the dosages we are discussing.

In short, even at relatively concentrated doses, fenbendazole does not harm seahorse fry when it is being used to eradicate hydroids from nursery tanks, so it should not be harmful to your dwarf seahorse fry in the insignificant amounts that gradually leach out of pretreated live rock. In fact, I know many dwarf seahorse keepers who use pretreated live rock in their setups, and they have reported no problems with it affecting their H. zosterae fry. As long as there are no sensitive corals or Astrea snails in your dwarf seahorse tank, I don’t believe fenbendazole-treated live rock would pose any risk for your dwarf seahorses or their offspring, and I recommend using it to prevent ongoing problems with hydroids and Aiptasia rock anemones.

In short, don’t hesitate to use live rock and live sand in your dwarf seahorse setup, Donna, providing you are willing to treat the aquarium with Panacur in order to eliminate stinging animals such as hydroids, Aiptasia rock anemones, and bristleworms.

However, although using the Panacur will protect your dwarf seahorses from the dreaded hydroids, it also means that you’ll need to avoid using soft corals that might likewise be of virtually affected by the fenbendazole. In other words, Donna, plan on using fake plastic plants or live macroalgae as the aquascaping for your dwarf seahorse setup in order to provide them with convenient perches and hitching posts.

Okay, Donna, that’s the secret to keeping dwarf seahorses successfully nowadays. Use live rock and live sand for the stability and additional biological filtration they can provide, which will make it easier for you to maintain good water quality in the dwarf tank. But then treat the tank with a three-day regimen of fenbendazole (brand-name Panacur) to eliminate unwanted pests that can be harmful to dwarf seahorses such as bristleworms and especially Aiptasia rock anemones and hydroids. Periodically adding small doses of the fenbendazole at regular intervals thereafter will effectively keep your dwarf seahorse tank free of hydroids and that tag and anemones at all times.

As for the film of green algae, I would suggest introducing some herbivorous snails that will feed on the algae. The Nassarius snails you are using now will clean up meatier leftovers, but they won’t help with the algae growth.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support