Crep. I got too cocky last post about my fish tanks.

First, a rundown on the 55-gallon display tank, in case any greabeard aquarist is reading and has sage advice for me.

I’ve had the tank for over twenty years, so it is well-cycled. (I replaced the filter last year with a new two-barreled biowheel filter, but I’ve verified there’s no trace of ammonium or nitrite in the tank, so that too is now well-cycled.) I normally keep the temperature at around 79F. My water parameters are around 10 to 20 ppm nitrate, 0.5 ppm phosphate, carbonate hardness 5 dH, general hardness 6 dH, pH out of the tap somewhere around 7.4 but I CO2 inject to bring it down to 7.0. The tank is planted with several dwarf cryptocorynes that are doing great, some dwarf anubias that is also doing well, several swords that are not doing quite as well, some ludwigia and bacopa that are struggling to get established, and some water wisteria that is not doing well at all. Animal inhabitants are an uncensused but fairly large population of Malaysian trumpet snails, two of what my local store calls zebra mystery snails, a very young Ancistrus cat, eight otocinclus, three Siamese flying foxes, two clown loaches, two Bolivian rams, and seven rainbowfish (two male Boesmani, three female Boesmani, and two turquoise.) Many of these are new stock I added two Fridays ago as a holiday spending binge — the ancistrus, some of the otocinclus, the two turquoise rainbowfish, the rams, and the Siamese flying foxes. I also purchased a 5.5 gallon tank on sale with thoughts of using it as a quarantine tank, but as it hasn’t cycled yet, I put just a single dwarf gourami and snail in it intended to closely monitor until it cycled, and put the other new ones directly in the display tank with as little of their old water as possible.

Last Saturday afternoon (not quite four days ago) I noticed some of the fish flashing, particularly one of the clown loaches. Took a close look, and, sure enough, there were several of the dreaded white spots on the loaches. Possibly one or two on the larger rainbows. The other inhabitants seemed unaffected so far. I began raising the temperature, leveling out at 90F last night and then dialing slightly back to 88F as the Siamese foxes were showing some signs of mild stress. The other inhabitants seem fine so far. I also began using a half-dose of malachite green Saturday. I’ve been vacuuming the gravel every day enough to change out 20% of the water, and redosing with malachite green on each water change in proportion to the water removed. The malachite green product I’m using apparently does not contain formaldehyde (not listed in ingredients and the stuff is odorless) but I have been regularly dosing with glutaraldehyde for algae control (and theoretically as a carbon source for the plants) so there is some aldehyde in the water to work with the malachite green. The tank is well aerated and so far the fish and plants seem to tolerate the treatment well, except for the flying foxes looking slightly stressed last night; they seem happier this morning with the temperature dialed back to 88F.

How soon should I be seeing results? I see no signs of any new fish being infested, but after three and a half days of treatment, the loaches still have numerous tiny white spots on them. I would have thought that at 88F these would already have dropped off the fish, and the heat treatment and malachite green/glutaraldehyde should be preventing any reinfection, no? I’m worried I have a strain of ich that is resistant to both heat and malachite green, or that the tiny white spots are something other than ich. (Sure look like it, though, plus the flashing.)

Meanwhile — separate mystery — I lost the gourami in the new tank. I had been monitoring ammonium daily and changing out most of the water at the first sign of any buildup, and the little guy seemed to be doing well. But Friday I came home to find he was showing classical signs of ammonia poisoning, listless and hanging just below the water surface. Crep. Checked the ammonium level; not a trace. No nitrite. I did two 80% water changes over the next two days and he seemed to briefly rally before succumbing last night. My guesses: An ammonium spike my tests somehow missed; or the fish got spooked somehow on Friday and smacked into the glass with fatal internal injuries (I lost a discus years ago that way.)

Anyway, I have the option now, if necessary, of moving the two loaches (since they are the only ones showing more than a spot or two) into the new tank — if I’m willing to take that risk — for more intense treatment. The display tank is infected, obviously, but with live plants, snails, and scaleless fish in it, I can’t risk full-dose malachite green or salt. I could do that in the small tank.


This article has 2 comments

  1. Kent G. Budge Reply

    The gourami finally expired. From lack of any signs of parasites or other disease, and lack of any ammonia in the tank according to the test kit, I’m going with the theory he slammed into the glass and suffered internal injuries he could not recover from.

    The fish in the display tank all seemed happy this morning. The loaches may be looking a little better; they seem to have fewer pinpoint white spots than last night. Fingers crossed.

    • Kent G. Budge Reply

      Long time realizing this, but: My nitrite test wasn’t registering properly. The poor guy probably succumbed to nitrite poisoning.

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