Re:Help Need Search engine

Pete Giwojna

Dear Cindy:

Yes, you can search this forum by word or phrase. If you look in the upper right-hand corner, just above the page numbers, you will see a small rectangular window with the words "search forum" in the box. Just type the word or phrase you are looking for in that rectangular window and press "Enter" on your keyboard. The search results will pop up in just a few moments.

Seahorse fry scratching themselves is a fairly common problem, particularly for the home breeder, and is usually due to parasites and/or infestation of hydroids. It certainly is possible that protozoan parasites are responsible despite the excellent maintenance, frequent water changes, and transfers to new sterile nurseries you are performing, Cindy. This is because the parasites are present on the seahorses themselves, most often their gills, and therefore make the transfers right along with the fry and are not all eradicated by simply making water changes.

There are a number of options that ordinarily relieve this problem. Professional aquarists typically treat the nursery tanks with formalin at the first sign of scratching. The newborns tolerate the standard 25ppm formalin dose (about 1 mL per 10 gallons of water) just fine. (Note 1 mL = 1/5 teaspoon or 20 drops.)

Or the formalin can be administered as a series of one-hour baths. The proper dosage for a one-hour bath is 1ml of formalin per gallon administered every other day for a total of 3 treatments. The fry also typically tolerate formalin baths very well.

Home breeders also report good results controlling scratching of the fry by dosing the nursery tanks with methylene blue. They will typically add just enough of the methylene blue drop by drop to tinge the nursery tank a nice shade of blue (just a light blue — not such a dark shade of blue that you cannot see the fry clearly or so that they cannot see the newly hatched brine shrimp clearly during the feedings). Either the formalin baths or the methylene blue might be a good place for you to start, Cindy, since adding formalin directly to the nursery tanks could be detrimental to the live rocks and would be trickier to redose properly following every water change.

Newborn seahorses also tolerate copper sulfate well, which will control most of the common ectoparasites, but I prefer the formalin baths since copper has the unfortunate side effect of suppressing the immune response somewhat. If you want to try the formalin treatments at 1ml/gal for a 1 hour bath every other day until the scratching stops for up to 3 treatments, be sure to observe the usual precautions outlined below:

Formalin Baths

Many commercial formalin products are readily available to hobbyists, such as Kordon’s Formalin 3, Formalin-F sold by Natchez Animal Supply, and Paracide-F, sold by Argent Chemical Laboratories. Or whatever brand of formalin is available at your fish store should work fine, Cindy. In essence, formalin is simply a 30% solution of formaldehyde and water.

A formalin bath simply involves immersing the seahorse in a container of saltwater which contains the proper dosage of formalin for a period of 60 minutes before returning it to the main tank. Include a hitching post of some sort in the container and follow these instructions: place the fish in a three-gallon bucket or a similar clean, inert container containing precisely one gallon of siphoned, aerated tank water. Medicate the bucket of water with with the appropriate amount of formalin for a concentrated bath according to the directions on the label. Place an airstone in the bucket and leave the fish in the bath for up to 60 minutes. If at any time the fish becomes listless, exhausted or loses its balance, immediately place the fish in clean, untreated water in your hospital tank.

I want you to be aware of these precautions when administering the formalin bath:
Formalin has limited shelf life and degrades to the highly toxic substance paraformaldehyde (identified as a white precipitate on the bottom of the solution); avoid using any formalin product which has such a precipitate at the bottom of the bottle.
Formalin basically consumes oxygen so vigorous aeration must be provided during treatment.
Time the bath closely and never exceed one hour of chemical exposure at this concentration.
Observe the seahorse closely during the bath at all times, and it show signs of distress before the allotted time has elapsed, remove it from the treatment immediately.

If you have live rock and/or live sand in your nursery tank, hydroids infestation is also a strong possibility, Cindy, since those are ideal conditions for hydrozoans. Examine your nursery tank carefully for any signs of the dreaded ‘droids or the transparent medusae. Here’s what to look for:

If you rear seahorse fry for any length of time, sooner or later you will have to deal with an infestation of hydroids in your nursery tank(s). Hydrozoans are colonial stinging animals that are the scourge of the seahorse breeder because they can take over a nursery almost overnight and wreak havoc on the fry. The typical hydroid colony has a stem with a variable number of polyps growing on it, and each of these polyps bears numerous tentacles that are liberally studded with knobby nematocysts (batteries of deadly stinging cells). There are many different kinds of hydroids and they appear in the aquarium in many different guises: many colonies are stalked; some have fingerlike projections, others look like tiny pink fuzzy balls or or resemble snowflakes adhering to the aquarium glass or appear like cobwebs (the webbing kind usually spread along the bottom or grow on the aquarium glass along the substrate).

Even a large hydroid colony appears harmless to the naked eye. It takes a much closer look to reveal the dreaded ‘droid’s lethal nature, as described in The Complete Guide to Dwarf Seahorses in the Aquarium by Alisa Wagner Abbott:

"Studying the colony under high magnification, one soon becomes lost in an extraordinarily complex, living world–a microcosm in which a beautiful but deadly ballet is conducted on a microscopic scale (Rudloe, 1971). Hungry polyps, some resembling snapdragons, others looking more like daisies or tulips, expand their knobby, translucent tentacles, slowly flexing and languidly waving them about, lulling the observer with their slow-motion ballet — until they abruptly and quite unexpectedly snap up a bit of planktonic life, stinging it, drawing it in with one violent contraction, digesting it, and then re-expanding like a blossoming flower to hunt again (Rudloe, 1971). There are many such polyps in a colony, hundreds of them, each of which is armed with many tentacles and countless nematocysts, and at any given moment, some of them will be dormant and still, some will be expanded and lazily casting about for prey (Rudloe, 1971), and still others actively feeding (Abbott, 2003)."

Hydroids are insidious because they start out so small and insignificant, yet spread so quickly. Many species can spread asexually by fragmentation as a microscopic speck of the parent colony. All of the troublesome types have a mobile hydromedusae stage, which look like miniscule micro-jellyfish, and can spread sexually in this way as well (Rudloe, 1971). The mobile medusae swim about with a herky-jerky, pulsating motion and are often mistaken for tiny bubbles due to their silvery, transparent, hemispherical bodies (Rudloe, 1977). These tiny jellies often go unrecognized until they begin to settle and are discovered adhering to the tank walls. They will have a large "dot" in the middle of their bodies and smaller ones at the base of their nematocysts (Abbott, 2003). Both the polyp stage and the medusa stage sting (Rudloe, 1977) and are capable of killing or injuring seahorse fry. Multiple stings can kill the babies outright, but they are often only injured by the nematocysts, which damage their integument and leave them vulnerable to secondary infections. Many times it is a secondary bacterial or fungal infection that sets in at the site of the injury which kills the fry.

Even if you see no evidence of hydroids, it’s still possible they may be present in your nursery tanks. In their initial stages they are so small and insignificant they may not be apparent to the naked eye. For example, close-up photography of the fry and the nursery tank will often reveal tiny hydroids adhering to the holdfasts or glass that were only evident when examining the macrophotographs at high magnification (Leslie Leddo, pers. com.)

A picture of the common snowflake type of hydroid is available online at the following link:

If you feel an outbreak of hydroids could be responsible for the scratching, Cindy, they can easily be eradicated from your nursery tank using fenbendazole (brand-name Panacur). This might be a good option in your case because fenbendazole seems to soak into the interior of the porous live rock and be absorbed indefinitely. Thereafter, the fenbendazole will gradually leach back into the aquarium water, where it can still take a toll on senstive invertebrates, including hydroids of course. For example, 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. The moral of this lesson is twofold: don’t treat live rock intended for reef systems with fenbendazole (Panacur) but by all means do treat live rock intended for a dwarf seahorse tank or nursery with fenbendazole!

When live rock is pretreated with fenbendazole, the gradual release of the Panacur that the LR has absorbed can thus provide a dwarf seahorse tank with long-term protection against hydroids. I know a couple of dwarf seahorse keepers who report good success using live rock pretreated with fenbendazole.

Fenbendazole is an 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) or via the Internet. The granular form of fenbendazole (horse dewormer granules 22.2%) is preferable to the paste for aquarium use, as the dosage of the granules is easier to regulate (Liisa Coit, pers. com.). It is available in packets of 5.2 grams or 0.18 ounces.

Carol Keen, Alisa Abbott, Liisa Coit and Pam Worden have all experimented extensively with fenbendazole for hydroid control. In general, their results agree. All found it to be successful in eliminating these pests. For instance, Coit and Worden have found that the effective dose for eradicating hydroids is 1/8 teaspoon of the horse dewormer granules (22.2% fenbendazole) per 10 gallons of water. This works very well with adult seahorses, but nursery tanks (or dwarf seahorse tanks with juveniles and fry) should be treated at half that dose because the delicate newborns are more sensitive.

Treat hydroid infested nurseries or dwarf seahorse tanks with 1/16 teaspoon per 10 gallons of water. Dose the tank with 1/16 teaspoon/10 gallons every other day until you have administered a total of 3 such treatments (Liisa Coit, pers. com.). By the third day of treatment, the hydroid colonies will begin to show the effects of the fenbendazole (Liisa Coit, pers. com.). All the polyps will begin drooping. This is most noticeable with the stalked kinds that attach to the tank walls. If any of the polyps or colonies have not gone completely limp by the end of treatment period, leave the nursery tank alone for another day or two before you do any water changes or otherwise pull out the medication (Liisa Coit, pers. com.).

Fenbendazole kills all types of hydroids but the hobbyist should be aware that the different kinds will die at different rates. Coit and Worden report that the finger types of hydroids are relatively difficult to eliminate, while the pink fuzzy balls are the easiest to kill. As a rule, the smaller the colony, the easier it succumbs. The stalked form of hydroids are intermediate in terms of toughness; small stalked colonies expire fairly quickly, but large colonies must be exposed to the fenbendazole for a longer period before they die off (Liisa Coit, pers. com.). Hardest of all to eliminate are the webbing kind of hydroids that spread along the substrate or on the tank walls like cobwebs, so treat accordingly (Liisa Coit, pers. com.).

Coit also notes that its important to leave your filtration running during the treatments, although chemical filtration media such as activated carbon must be removed for the duration. Everything in the infested tank, including the equipment, needs to be fully exposed to the fenbendazole to make sure there is no recurrence of the hydroids.

Likewise, all of your nets, brine shrimp hatcheries, hydrometers and associated aquarium paraphernalia must be sterilized while the aquarium is undergoing treatment, or your tank will be rapidly re-contaminated with hydroids, leaving you right back where you started (Liisa Coit, pers. com.).

Because fenbendazole is essentially a de-worming agent, it will destroy any bristleworms, flat worms, spaghetti worms or the like in the aquarium. Keep this mind if you have live rock and/or live sand in the treatment tank — a massive die-off of the worm population will require large water changes in order to prevent a dangerous ammonia spike!

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 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 (Abbott, 2003)! This shouldn’t be a problem in a dwarf seahorse setup or nursery tank, however.

At the lower dosage recommended for nursery tanks (1/16 tsp. Per 10 gallons), fenbendazole normally does not harm cleaner shrimp and decorative shrimp. With the exception of Astrids, Coit and Worden have found it does not affect the types of snails typically used as clean-up crews (e.g., Nassarius, Ceriths, and Nerites).

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.

Fenbendazole (brand name of 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) or via the Internet from places such as KV Vet Supply (see link below). The granular form of fenbendazole (horse dewormer granules 22.2%) is preferable to the paste for aquarium use, as the dosage of the granules is easier to regulate (Liisa Coit, pers. com.). It is available in packets of 5.2 grams or 0.18 ounces.

Click here: KV Vet Supply / KV HealthLinks – Pet, equine & livestock supplies / Quality nutrition for you!

(Use the 22.2 % granules rather than the paste.)

If your tank is free of hydroids, then it’s very likely to be a parasite problem of some sorts, Cindy. It could be ectoparasites that attack the skin and gills (Uronema, Cryptocaryon, Amyloodinium, Costia, Cryptobia, etc.), or nematodes, or — well, or a whole lot of things. Doesn’t really matter. The formalin baths are helpful against all of the above.

So this is what I would suggest in your case, Cindy. Start treating the scratching fry with methylene blue and/or a series of formalin baths as discussed above right away (both the formalin and methylene blue will be available at any well-stocked LFS). In the meantime, order the granular form of Panacur, and while you are waiting for it to arrive, you can complete the anti-parasite treatments we have been discussing. If they don’t put an end to the scratching, then you can go ahead and treat the nurseries with fenbendazole as soon as it arrives.

Best of luck relieving the scratching of the seahorse fry, Cindy!

Pete Giwojna

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