Hello all, so I'm fairly new to the hobby but have put a lot of effort into learning as much as I could. I have 6 gal nano tank where I've had seven cardinal tetras and 2 otocinclus for about 3 months now. I realized this tank was to small so I bought a 20 gal. I cycled the 20 gal for 2 weeks using dirty sponge filter and beneficial bacteria (api stresszyme) to jump start nitrogen cycle. This past Sunday I purchased some more tetras (red phantom & pristella) and several corydoras. the red phantoms have been dying daily daily. I am down to 2 now. I've noticed very few white spots on them so immediately I began ich treatment with daily water changed as well as salt and heat. All my other fish seem okay. other than being stressed from the heat and salt. Ive seen videos and articles where ich need to be fairly advanced to kill and I've not seen any of my other fish with spots nor have any of them died. I also read that the white spots are supposed to multiply rapidly of which I've also not noticed. Before my fish die they begin erratic swimming and seem like they can't really control themselves and get swept by the water flow. Sometimes swimming upside down and on their side. They also hide and stay alone. Im now doubting it is ich and would like to know if anyone else has experienced something like this. Thanks in advance