It's a 14 gal with a few livebearers and a betta. Some months ago, this tank had ich, and I treated with salt and heat which worked great. Thought I should point that out, just in case this could be related. A while ago I started to notice my two red wags sitting on the substrate with their fins clamped. This is what they started doing a week or so before ich symptoms had started in the past, so I was watching for white spots, which never came. The fish haven't had any ammo or nitrite exposure and the nitrates never exceed 20..are usually kept more around 10. Eventually the red wags color started to look a bit patchy..didn't exactly look like anything I'd seen before but I thought maybe the bettas gills looked like they were dusted a bit..so was thinking possibly velvet. Still didn't seem right though. One of the red wags started spending it's days sitting at the top of the tank swimming in one spot against the filter flow. It's very strange. Though seemingly weak, this put her in a position where she had to work hard all day. I added one tablespoon of salt per day for three days, slowing raising the heat a few degrees as well. Now in the past, treating ich or velvet, the fish have started to show almost immediate improvement after adding salt..not the case here. One red wag is now upside down, the other laying and hiding. Now another fish is scratching herself on things and her fins looked clamped as well. Still others are still acting and looking fairly normal. I'm guessing maybe this is some sort of parasite? Is salt the best treatment? If I do a mela/pima combo, I can only do 1/5 dose because there's a betta in there. Any advice appreciated.