Re:lighting for dwarf hippo.

Pete Giwojna

Dear hobbyist:

Your 9300k bulb should more than suffice for a dwarf seahorse tank. When it comes to lighting, seahorses do not have any special requirements other than the fact that most species (including Hippocampus zosterae, the dwarf seahorse) prefer low to moderate light levels rather than excessively bright light. They have a corrugated retina especially rich in rods, which gives them excellent visual acuity under twilight conditions and low light levels in general. Some species are even believed to be nocturnal (e.g., Hippocampus comes and H. ingens) and have no trouble seeing and feeding at night.

So either an ordinary incandescent bulb or standard fluorescent tube will work great for a dwarf seahorse tank. Between the two, I would strongly favor a fluorescent light fixture because the fluorescents give off less heat (overheating and heat stress can become problems for seahorses during summertime heat waves) and because the fluorescents are more economical to operate. Easier on the old electric bill. A standard daylight fluorescent will provide plenty of light to maintain the macroalgae in a dwarf seahorse.

You mentioned that you are using live rock and live sand in your dwarf seahorse setup. That’s excellent for supplemental filtration and adding stability to the tank, but it also means that you are going to have chronic problems with hydroids and Aiptasia rock anemones unless you take special precautions to control them.

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 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, you’re going to have an ongoing problem with hydroids and likely also app Aiptasia rock anemones in your dwarf setup, and that’s a cause for 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, app Aiptasia rock anemones, and bristleworms from your dwarf seahorse tank. Treating your 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.

You can also fenbendazole granules in small quantities online from the following vendor:

However, there are a couple of things you should keep in mind when treating an aquarium with fenbendazole, Sean. 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. The FBZ or Panacur treatments are best administered to the live rock in a bucket or hospital tank before the LR is introduced in the main tank. Otherwise, the massive die-off of the worm population in the aquarium may require large water changes in order to prevent a dangerous ammonia spike! And after the treatment is completed, its a good idea to add a portion of newly purchased live sand to the system in order to help restore its normal diversity of fauna and microfauna again (Liisa Coit, pers. com.).

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!

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)!

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 should be quite safe for dwarf seahorses and their fry, and because it 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 hydroid’s and app 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 a couple of 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 would recommend treating your dwarf tank with a regimen of fenbendazole before you add any ponies.

If you contact me off list ([email protected]), I have a lot of additional information on keeping and breeding dwarf seahorses that it would be happy to provide for you and your daughter to help assure that everything goes smoothly.

Also, if you haven’t already done so, I would also suggest that you pick up a copy of Alisa Abbott’s guidebook titled Complete Guide to Dwarf Seahorses in the Aquarium. That’s one book every Pixie owner and dwarf seahorse keeper should have on hand. I’ve proofed Alisa’s dwarf seahorse book for TFH publications and wrote the preface for it, and I highly recommend it! You can order a copy from Ocean Rider are any of the major booksellers.

Best of luck with your dwarf seahorse setup. That should make a marvelous birthday present for your daughter!

Happy Trails!
Pete Giwojna

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