Hello.
I’m new here, obviously; I’ve been lurking here on and off, but I have decided to make an account.
I have a parasite problem right now in a
10 gallon tank housing two P. anjunganensis and a small shoal of Boraras urophthalmoides (primarily as “dither fish”). Everyone has been healthy and tank parameters are up to par, but on Sunday (last weekend) I noticed that one of the boraras had some tiny lesions/cysts on its body. I examined the other fish, and while the “Paros” seem to be fine, I had to isolate five of the boraras because they either had obvious similar cysts/lesions or looked like they were developing them.
It took a couple of days to isolate all of them because the last two were very hard to capture (the tank has a very complex hardscape with tangles of moss, java fern, and ceratopteris, plus floating plants), but now all are isolated in a “hospital tank” and I am treating them with a formalin/malachite medication at a reduced strength.
I am not quite certain what these cyst-like lesions are being caused by, but I am certain that it is a protozoan parasite, because everything about the cysts/lesions matches. Furthermore, one of the boraras died, and prior to its death I removed it from the hospital tank (it was the “runt” of the shoal and it had a heavy load of encysted parasites relative to the size of the fish) and took a skin scraping to put under the microscope. Sure enough, I saw swarms of tiny organisms escaping from cysts and moving about the slide in loose aggregations.
I suspect that this problem arose from one of two sources/events:
1) I live in Oregon, near Portland, and we had a heat wave sweep through over the last two weeks; temperatures soared to near
100 deg. F, so I unplugged the heaters on all of my tanks to keep from overheating the fish. The heat wave then subsided, and after it appeared to have gone I plugged the heaters back in, but the water still cooled to roughly
71 –
72 deg. F for a short time. If the parasites were already in the water, this may have reduced the immune activity in the fish just enough for them become infected.
2) I recently (about a week ago) purchased some Ceratopteris pteridioides plants from a new aquarium shop that opened up very close to my house. The shop is run by a highly reputable fellow who has been active here for quite some time, and there were no fish in the tank with the plants, so I thought nothing of quarantine. Given the current timeline, it seems possible (unfortuntately) that I acquired the parasites from these plants.
In either case, I have no guarantee that the tank (current occupants are now three boraras and the two Paros) is parasite-free. I recently purchased a bottle of peat extract from a garden shop in the hopes of using it to help keep the water conditions I need going, and I decided to refresh my memory about humic acids here:
www.skepticalaquarist.com/humic-acids
This article mentions the following in the third paragraph:
“humins affect the cycling and bioavailability of chemical elements; they repress many bacterial populations and affect the zooplankton: acidic blackwaters rich in humic acids have characteristically low populations of bacteria and a depauperate zooplankton.“
Since common protozoan fish parasites have a free-swimming stage that needs to attach to a host (plus another stage that rests on the substrate or other solid surfaces), and one could consider the free-swimming stage zooplankton (and neither the substrate-bound stage or the free-swimming stage are protected by host tissues), could these be susceptible to a reduced pH brought about by additional humic acids?
I could easily bring the pH of the tank down to less than
6.
0 over the course of a day or two. I have been extremely busy lately, so I have not been able to closely regulate the water parameters, and the pH is slighly above
6.
0 and I do not have as high a tannin/humic acid concentration as I would like. The fish would obviously prefer this, but it may be a creative way for me to make life difficult for any other parasites that may be attached to fish undetected or hiding elsewhere.
I decided to ask this question here because this board is full of people who have to play around with humic acids by definition, and I was wondering if anyone knows if they can inhibit protozoan parasite activity in a tank with fish that prefer blackwater conditions anyway.