I know; this is supposed to be a geology blog. But we’re having a cold, wet winter. That’s always a welcome thing in the high desert of the West, but it does interfere with getting out into the field and looking at rocks. The trails are still snowy or muddy hereabouts. If the present somewhat warmer and drier weather holds, I might get onto a trail in a couple of weeks and have some pictures to post.

I was planning a trip to southern New Mexico as well, to collect at Kilbourne Hole; but my realization that the area was recently included in Organ Mountains National Monument and collecting is now forbidden has, I confess, sucked a lot of the enthusiasm out of that idea. The monument web site makes noises like the ban on collecting may be temporary, until BLM decides that the xenoliths are sufficiently abundant to permit collecting; but I am skeptical. So far as I know, not a single national monument or park permits any rock collecting within its boundaries. This is one reason I tend not to join the rejoicing whenever a new monument or park is proclaimed.

I’m not lacking for interesting things to learn about, though. I’ve been touching up my history site here and there. This was a much bigger project a decade ago, pretty much consuming all my leisure time, as you can imagine when you look it over. Is it finished now? Well, it will never be entirely finished, but it’s close enough that it’s now an occasional project.

I’m also preparing for the Los Alamos Choral Society winter concert, on February 17th. 4:00 P.M. Duane Smith Auditorium. Our program will start with Mozart, Ave, Ave, Corpus Verum, a beautiful short number that demands little of the listener. This will be followed by Copeland’s The Promise of Living, which is pretty typical Copeland: It demands more of the choir than the audience. Our first half will end with Ives’ Psalm 90, a very modern piece that demands much of both choir and audience. Like oysters or tonic water, it’s an acquired taste.

The second half will be Beethoven’s Mass in C Major, one of his earlier works, which deserves more attention than it usually gets. Is it baroque or romantic? Exactly. It is scored for choir and solo voices; we have an excellent tenor in Rene LeClaire, and a number of fine women soloists, but we’re scraping the barrel for the bass soloist.


Okay, I had a couple of years’ worth of voice training, but that was decades ago. My pitch is good, but not perfect. I never could learn to roll my R’s. Don’t let that scare you away from the concert, if you’re inclined to such things.

Finally, I am spending much of today prepping a corner of the basement for painting. Long overdue. I did much of the upstairs last year, and it was a vast improvement. The challenge with the downstairs is three massive bookcases (my library), a massive computer desk, and a massive 55-gallon fish tank.

The last of which has been my biggest preoccupation lately.

Last Friday, I added quite a few new fish to the tank. The next day I saw the loaches flashing; that is, scratching their sides against the sides of the tank. This is a classical symptom of infestation with ich, Ichthyophthirius multifiliis, the most common and (alas) often deadly disease of aquarium fish. Inspection of my fish showed the other classical symptom: Tiny white dots on the skin of the fish. Only a few spots on the other fish, but many on the loaches. They’re unusually susceptible, for reasons based on the life cycle of the parasite.

Ich is a ciliated protozoan, distantly related to the Paramecium that are a staple of introductory microbiology classes. The life cycle begins when a tomont, the reproductive phase of the parasite, bursts open and releases up to a thousand theronts, the infectives stage. The theronts are free-swimming but can survive less than 48 hours unless they find a host. Once they latch onto a fish, they burrow through the mucus coat and into the skin, where they feed on skin and blood cells. This gives them their generic name: Ichthyophthirius = “fish louse.”

Once attached to the host, the theront becomes a trophont, the feeding stage of the parasite. The length of the trophont stage is highly temperature-dependent; in 50F water, it can last a month, while in a warm aquarium (80F) it lasts just a couple of days. Either way, the fish is irritated by the constant movement and feeding of the parasite, its body walls off the parasite into a small cyst that is the white dot seen on infested fish, and the fish may try to dislodge the parasite by flashing.

One engorged, the trophont burrows back out of the mucus layer, drops to the bottom of the tank to attach to the gravel or a plant, and encysts to become a tomont. Within less than a day, the tomont rapidly multiplies to produce hundreds to a thousand tomites. This gives the parasite its species name, multifiliis, “many children,” so that an ich is a “fish louse with many children.” The cyst then ruptures to release the tomites as theronts, completing the cycle.

Hence the susceptibility of loaches. They’re bottom-feeders, spending most of their time sniffing at the gravel at the bottom of the tank — and getting an extra-heavy exposure to the therodonts emerging from mature tomonts. They may also be physiologically more susceptible, though since ich exists in nature and loaches are bottom-dwellers there, too, I don’t know why that would be, unless it’s that the ich is more adapted to attacking bottom-dwellers.

The ability of the organism to produce a thousand offspring in a single reproductive cycle, which may take as little as three days, explains why the organism is so dangerous in a fish tank. Here there is a nice warm environment with ample substrate for the tomont stage and several potential hosts in close proximity. The resulting population explosion can leave the fish so infested, particularly in their gills, that they simultaneously suffocate and lose vital electolytes through their damaged membranes. Untreated ick in a fish tank is often 100% fatal to the fish.

So how do you save your aquarium? Here is where there is a host of information online, much of it factual. ­čśë

First, while it is likely that stress increases susceptibility to infection by weakening the immune system, even a healthy, happy fish is going to be in big trouble in a tank full of theronts. There is, so far as I can tell from the more reliable sources, no resting stage, and subclinical infections (low-grade infections producing no symptoms) that smolder for months in an aquarium fish seem implausible given the life cycle of the organism. Ich very often appears in tanks to which new fish have been added, and it is very likely that the new fish already are subclinically infected somewhere along the supply chain from the wild or a fish farm to your local aquarium shop.

The organism is often susceptible to high temperature. Many sources claim that ich can be eradicated simply by raising the tank temperature above 86F, which prevents the organism from successfully reproducing. And it seems to be true that at these kinds of high temperatures, typical of discus tanks, ich is less of a problem. However, it is increasingly common to hear reports of strains of ich that are unaffected by any tank temperature that is safe for the fish.

Failing heat treatment, another older remedy is to add salt to the tank. This helps reduce electrolyte losses from the damaged membranes of the fish and seems to slow down the ich, but it is also apparently unreliable as a way to eradicate an infection completely. Heat and salt together are sometimes enough, if it’s a susceptible strain, and so some aquarists swear by it. But salt at levels likely to affect ich will not be tolerated by the plants in a planted aquarium, like mine.

The final non-medical remedy is to separate the fish from the theronts. This can be accomplished, in principle, by moving the fish every day into a new sterilized tank while bringing as little of the old water as possible with them. The tomonts are left behind in the old tank, and when they hatch, the therodonts can find no host and die within 48 hours. Or you can thoroughly sterilize the old tank, which now has no fish in it. No stage of ich can withstand thorough drying nor can they stand up to disinfectants like household bleach or hydrogen peroxide. The problem is that moving the fish every day is quite hard on the fish, and many of us do not have spare, clean tanks ready to receive the fish.

That leaves using some kind of medication to kill one or more life stages of the parasite. Here the problem is the usual one with medical therapy: It has to be a lot more lethal for the parasite than the fish. There is not much you can get into a fish that will kill a trophont that won’t also kill the fish. Likewise, the tomont/tomite stage is encapsulated in a cyst that is relatively resistant to disinfectants at levels that won’t hurt the fish. So the usual target is the free-swimming therodont stage. This means that medication must be maintained at levels lethal to therodonts for long enough that all trophonts will have finished feeding, detached from the fish, gone through the tomont/tomite stages, and hatched their therodonts.

There are a number of medicines effective against therodonts. All involve tradeoffs.

I began treating this tank by cranking up the temperature to around 90F, in the range where heat alone will often halt an infestation. It took until Monday for temperatures to reach this value. I also dug out an old vial I have on hand of a chemical called malachite green. This is a benzyl dye, composed of three benzene rings attached to a carbon atom and decorated with a couple of amide groups. Notwitstanding its name, it has no copper in it and it’s not actually green; it appears sky-blue to my eyes at lower concentrations, with perhaps a hint of aquamarine, and I’m not colorblind. The stuff is fairly lethal to some fungi and most protozoan parasites, including (particularly) ich therodonts. It can also irritate some fish, including cats and loaches, and the two most infected fish in my tank were the two loaches. So I went with a half dose. The instructions called for a single dose, a half water change the next day, and repeat the cycle every three days. I modified this to changing out 25% of the tank water each day and giving a third of the dose after the change, thinking this would be more uniform dosing, less stressful on the fish, and would allow me to vacuum some of the tomites out of the gravel on each water change.

Monday, when I got home from work, the tank was nice and toasty warm. Alas, the Siamese flying foxes were showing clear signs of stress; I dialed back to 88F, still supposedly enough to stop the ich, and they looked better. I figured between high temperature and half-dose malachite green, I was covered, and the infestation would be gone in a few days.

By Wednesday there was no sign of any such happy outcome. The infection wasn’t running wild, but I was seeing a few more spots on the other fish, and the loaches seemed as heavily infested as ever. Obviously not working. Snow.

This ich had continued multiplying even at 88F and in a tank half-dosed with malachite green. A super-ich. Unfortunately, this is not terribly surprising. With a five-day life cycle at normal temperature and a huge reproductive rate, the parasite can be assumed to mutate rapidly, and we can expect to see resistant strains emerge more and more often.

I could not try heat and salt. Planted tank.

Well, my vial of malachite green was almost empty anyway, and it was over twenty years old. Sure, the stuff is supposed to keep indefinitely in storage, but maybe not. I did some more research. Copper salts are effective, but they’d kill my plants and my snails. Methylene blue can be effective, but it’d kill my plants and my biological filter. Quinine sounds like the definitive treatment; ich is susceptible, and the stuff is easy on the biological filter and the critters and plants. Furthermore, it’s just possible that enough gets into the fish that it affects trophonts. Alas, getting ahold of a few grams of quinine on short notice is a bit of a problem. I asked at my pharmacy; no dice. FDA has banned it for relieving leg cramps, the only likely use in a North American pharmacy. (It’s rarely even bothered with against malaria any more, because so many resistant strains have evolved.) No dice with my vet. “Try Amazon.” Amazon apparently has it, but only in minimum $50 lots and maybe not to ordinary customers nor in time. Or you can buy homeopathic quinine, meaning very pure water wearing a fraudulent quinine label. Or you can buy herbal extracts of chinchona of low purity and uncertain strength.

Or you can try having your fish swim in tonic water. Except that the correct dosing would be a problem even if the fish could tolerate the carbonation and citric acid.

Too bad. Apparently the best treatment ever sold was a mixture of malachite green and quinine; no longer manufactured or readily available. I decided I’d spend my Friday off, yesterday, visiting fish shops in Albuquerque and Santa Fe and see what they had.

So I headed first to the Petsmart in Santa Fe, mostly because it was along my way anyway. The choices included an herbal cure, which I didn’t even consider; placebos sound unpromising for fish. There was also a Marineland ich medication based on “Victoria green” (an alternate name for malachite green) and nitromersol. I didn’t know what the latter was but it sounded promising and I almost bought the stuff. Turns out it’s a mercurial; similar to thimerosal. Might have worked. Finally, they had fizzy tablets containing malachite green and acriflavine. The latter is a malaria drug, and also might have worked; but I was unfamiliar with it, this stuff would have been expensive for dosing my big tank long enough, and I decided to keep looking. Not before visiting the kitten display; cats from the local shelter up for adoption. Squeee.

I headed on to Albuquerque. I had a list of fish shops from the Internet with directions, and I really wanted to just get this done. The first was Westside Pets. Not a bad little shop, but somewhat limited in its selection; they added a Jungle product that didn’t seem to offer much different from the others, and their supply was less than I’d need for my big tank for long enough.

Next was Clark’s Pet Emporium in the Nob Hill area. I think I used to shop here when I lived in Albuquerque, and it’s a big, impressive store. They had several options, including metronidazole. The stuff is a big-gun antibiotic effective against protozoa, though a bit pricey. I went ahead and bought some as a final resort if needed. Then I checked out the fish and plants; they have Vallisneria, which I’ve never seen at Petsmart, and they keep in in separate tanks from the fish, a good sign that they’re serious about parasite control. I’ll probably be back.

Finally the other Clark’s on Menaul. This was even more impressive than the first, and it’s very near the Latter-day Saint temple, so it’s convenient to shop at after attending a temple session. I’ll certainly be back, to pick up V allisneria and possibly more fish.

There was an in-shop expert at the shop, who when he heard of my difficulty, strongly encouraged me to use a formaldehyde-based product. Formaldehyde can be quite effective against ich. It’s often combined with malachite green, and the malachite green-formaldehyde combo seems to have a synergistic effect that makes it possibly the strongest first-line ich treatment still widely available. The expert recommended formaldehyde alone, telling me the malachite green would be too much for my plants. They also had some Paraguard, which I had already ordered from Amazon, but which would not arrive until next Wednesday at the earliest. This stuff is a variant of the malachite green plus formaldehyde; it uses gutaraldehyde instead, which may be easier on sensitive organisms (hopefully not including the therodonts.) Well, I’ve been using glutaraldehyde for weeks in my tank already as an algae suppressor; obviously the ich didn’t mind it. I finally settled on a product that kept coming up online, Kordon Rid-Ich Plus. Short of the metronidazole, it’s probably the strongest stuff available, and would require some care to use without killing the fish or plants, but I decided it could be done. If the fish started suffering from it, I’d change out half the water and go with my final resort, the metronidazole. Metronidazole disrupts DNA, but only if reduced; and while protozoa will do this and then succumb, higher organisms will not reduce the compound and so will be unaffected. This means it shouldn’t affect biological filter or desirable critters and should be lethal to the ich. The catch is it’s expensive and, like all antibiotics, not to be used lightly lest one create a resistant strain of ich.

So I proceeded home, stopping first for lunch at Golden Corral — great for filling your stomach with moderately nutritious food as quickly and cheaply as possible — and then at the pet store in Santa Fe for some algae wafers. Stopped by the cats again; one tortoise tabby let me scritch her head through the bars of the cage. Again, squee. But we got five cats already even if I was ready to pay the $70 adoption fee. Got home and began dosing.

There are three things to watch out for with malachite green – formaldehyde combos. First, the chemicals can be irritating to some more sensitive fishes, including loaches. My loaches looked awful enough by now that I was prepared to take that chance. If worse came to worse, I’d move them into the small tank which would require less metronidazole for correct saturation. Second, the formaldehyde oxidizes to formic acid, lowering the pH in the tank. Malachite green is more toxic to fish in soft water or at low pH (the two tend to go together, so it’s not clear which is more crucial.) My water is normally not very soft, with a carbonate hardness of 6 dH, and its normal pH is 7.4 out of the tap; I normally carbon inject to pH 7.0, but I’d have to watch the pH in my tank carefully. Finally, formaldehyde oxidizing to formic acid depletes the oxygen in the water; I’d have to watch for signs that more aeration was needed. Fortunately, my tank has a double-barrel biowheel filter that stirs up the water pretty good, and I could always crank down the temperature to increase oxygen solubility, since the higher temperature wasn’t controling the ich anyway.

So far? It’s only been a day, but I think I see slight signs of improvement. One loach seems free of spots now and the other fish show very few. The other loach still looks pretty bad, and he’s off sulking by himself. I tried moving the loaches into the smaller tank, but they showed impressive energy as soon as the net approached; I finally decided that it was going to be a lot of work to catch them, and it would stress them out so bad it might do more harm than good. I considered trying again this morning, but Cindy sensibly said, “They’re not feeling good. Leave them alone.”) So unless they get so sick they are too weak to evade the net, they’ll take their chances along with the other fish.

Which are mostly doing okay. The rainbows are spending more time than I would like hovering just under the water surface, a sign of low oxygen, but I’m slowly cranking the temperature down to help with that. And it’s not a critical oxygen shortage yet; they are still feeding normally, and the other fish are showing no signs of oxygen deprivation.

Fingers crossed! If I can’t get the oxygen level up, and have to reduce the dosing, my last resort is the metronidazole. Wish me (and the fish!) luck.

This article has 1 comments

  1. Kent G. Budge Reply

    Discovered while cleaning the tank yesterday that the filter was badly plugged with plant debris and this may explain why the oxygen levels were low. Once cleared, the filter was moving a lot more water, and the fish soon looked happier.

    One loach is back to eating again. Oddly, it’s the one most thoroughly encrusted with white spots. The other is still sulking. Other fish look very happy in spite of a day and a half of bathing in formaldehyde and malachite green. Is it working? Too early to be sure, but I think I’m seeing slightly fewer white spots. The one loach is my measuring stick; still covered with tiny white specks. Once he’s clear, I continue treatment for a week just to be sure no more tomonts are hatching, then put my carbon back in the filters, start slowly lowering the temperature, and hope for the best.

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