Okay, so I figured out that what I thought were bubbles on the skin of my 4"-5" channel cat fingerlings is actually advanced ichthyophthirius infection, so I've transferred as many as I could catch (not easy in a filled 275 gallon IBC) into a salted water tank--not heated, because I don't have a heater.
I am reluctant to salt the water in my AP system, since I use waste water from it to fertilize/irrigate my soil garden, where I don't water heavily enough to not have to worry about salt build-up.
So far I have not seen any symptoms on any of the other fish--fathead minnows and weather loaches have been sharing water for a while, and I just put 14 black bullhead in yesterday. There are still a handful of infected channel kitties in with them. Is it reasonable for me to hope that my loaches, minnows, and bullheads (all adult fish) might be successful in resisting the parasite?
One kitty died and another is swimming in circles. All the others still have the white bubble-like spots. I upped the dose of salt a bit this evening and added some epsom salt as well.
Okay now it looks like my loaches have ich as well. Just a matter of time before the bullheads start showing signs. I'm going to slowly crank up the salinity to 3 ppt (or for the biologists, I'm calculating this at around 115 mOsm/L--about half-strength isotonic saline for freshwater vertebrates) to see if I can't eradicate this parasite. I'll leave it like that for a few weeks before doing water changes to get the salinity down to a level that's safe for aquatic plants (I want to put a wasabi in a pot in my sump tank) and safe for using the water for my soil garden.
I plan on using a hydrometer to monitor salinity levels. Anyone have experience with that?
All the channel cats are toast, and I just netted a bullhead with ich out of the fish tank--I'll assume they all have it.
I still need to add another 3.5 kg of salt to get things up to 3ppt, but man--the API aquarium salt takes forever to dissolve.
Assuming I can get the salt levels up soon, should I be expecting any problems with my plants? Do the ich cysts last for long in the media beds--will four weeks at 3ppt be enough for a total eradication?
I don't know much about salting, or ich, but I remember hearing that temperature fluctuations are a cause for ich...Getting a heater to stabilize your temperature might help prevent ich in the future.
Okay, I'm throwing in the towel.
I think the best thing for me to do now will be to euthanize all of my fish and let the parasite die out. I'm positive that it's ich (Ichthyophthirius multifillis), and from everything I've read there is no restive stage or non-fish hosts, and therefore if I keep my system fish-free for a couple of months through the warmth of summer, that will be adequate to eradicate the ich parasite. Basically just by taking away suitable hosts, they should die out entirely, and I can start back up again around July.
In the meantime, I won't need to elevate salt levels, and I'll keep my plants and bacteria happy by dosing with ammonia and supplementing with Maxicrop and worm tea.