So, a sunday market opened in front of my building a month back. There were a lot of fish, and live catfish. They were kept all together, struggling for air in a plastic box with only a bit water. There were mainly over 20 inches. I saw one which was only 10 inches and struggling to stay up and I just had to get it home. I thought if I had the time, why not(gap year, 17, just graduated). I am the idiot who thought the fish was strong and it would be easy. Oops. They gave it to me at 1/6 of the price cuz i said i planned to keep it as a pet. They gave me basuc instructions on keeping it alive till i had to let it out on a lake- 3/4 filled bucket with salt; 1/2 covered top; feed anything like worms or small pieces of meat. It was pretty fine in the bucket with miniscule chicken strips. Then it slooooowed down. My friend copied me with the adopt catfish and she suggested getting a tank. I got a 17 gallon tank with stones, a filter, a few plastic plants and some kind of blue medicine that i was told to add with salt. I was also given some red fishfood and dried shrimps. It got worse and the tank got dirty. I had added another, a bit smaller, channel catfish for company. It got white(columnaris?) and stopped eating. The first one also had a loss of appetite. I immediately got them out of the tank into separate buckets with salt and a miniscule droplet of the blue medicine. I also removed(permanently) all the stones and plastic plants. I checked up on the net for those ^. It also said to cull the white one, but I just couldn't. At the end it just floated to the bottom of the bucket and I just had to. Well, I just wrangled his(yes, i checked) brain. My original one was still okay. But no/barely any food was being eaten. I had to change the bucket water once oer day but sometimes twice Later, I got some freeze dried tubifex worms to be given in cubes. I was told the food given to me was WRONG, capital letters. ----> Coming to the point I washed the whole tank, now empty. Put in 16 gallons of water, with 2.5 teaspoons of salt(I know; idiot) and three drops of the mysterious blue medicine. 1/5 of the 3 litres of water in her bucket was a part of the 16 gallons I let the catfish in. She seemed stressed(which people keep saying is BAD). My filter is a double( even u have no idea what that means) one which they said meant that the tank needs to be cleaned only once in 4 months(WRONG). There was a oxygen thing, but it semi-electrocuted me so I removed it before letting her in. She got pretty relaxed soon. I later noticed her skin literally peeling off. IT WAS NOT THERE BEFORE SHE GOT INTO THE TANK. It's smooth peeling off, like we are supposed to do for cooking. I can see RED muscles or whatever that fish have. It's only happening to her belly side, in one thin strip, down the middle. I am scared. I don't want her to die. She has survived to 11 inches. I took out 6 gallons and replaced it with saltless water. And this is when I added water from her old bucket. Is it the blue medicine(Fish cure, all in all. dosage- 1ml for 5ltr, injuries parasite bacteria and fungal, 3 days treatment, i was advised to use a smaller dose as a avoid-all) ? Is it the bit of electric shock the water got for about 5 seconds BEFORE she was let in? Is it something else I mentioned? Is it the white thing( columnaris?) affecting her finally? Is it lack for bacteria/ need to cycle? Is it that the tank has an OPEN TOP- she kept jumping, hitting, banging against it and cutting herself so I had to remove it- ? The tank is kept in a corner of my room, only air, no non artificial light. MORE IMPORTANTLY- What do I do? How do I keep her alive and painless. Or do I need to cull her too cuz pls, I can't. She is swimming as usual an deven started eating- ONLY HER SKIN IS PEELING OFF. ~Bohnita, stupid stupid girl. ps- should i watch out for maggots? how do i avoid them? And she hates me+ is scared of me now- she used to come out of the water to nudge my fingers when i fed her. sometimes. but that comfy. what happened? That on the left is not her fin Ah, look at her eyes full of suffering suspicion. Doesn't she just lovve me ? aster- as i said, this was to keep the little baby alive. They already have a lake i will pass her onto within the year ... if she lives till then It seems there are more like her, small catfish that seem to get killed or eaten easily and they(the sellers) thought it better to just skip the stress,mrunning away and eventual pain. They also asked if i could keep more from time to time till they go up 15 inches or more. I would hooe to keep more together to let them interact but not if I end up being the cause of their death. So, yeah, theres a small lake of fish and the channels myseriously appeared. So i can put them back when they grow. possibly I just replaced 6g again. I also decreased the speed/pressure of the filter by closing the lid on the tube a bit further. Things seem to get better. Are any of the wuestions I asked valid or just random worries? Is the blue liquis methyl blue or somethings?