So here's the story: exactly 1 month ago, I got 2 bettas, my first fish. They were fine until about 3 weeks ago, when one of them started not eating and staying at the bottom of her tank (1 gal). For three days or so that was it, I'd put the little pellets (5 in the morning & 5 at night - btw I've always wondered if this is too much even if it's what the petshop guy told me) in the tank and they'd sit for an hour without her caring, then I'd scoop them out. Then she suddenly got a lot worse - she'd go up for air and then not even really swim back down, she'd just let herself "fall" in whatever way. Sometimes she'd be nearly vertical or sort of leaning on her side...And her skin got very strange, it looked like it was peeling. It wasn't just white dots and it wasn't cottony, though I had noticed some whitish film on her fins. But I could definitely see parts of her skin flaked/raised up. This was on one day, and the next morning (Monday) she had passed :(
I had put her in a bowl separate from my other betta, and he had been fine throughout. Swimming, eating, curious. Then just yesterday he started not moving so much, staying either at the bottom or at the top of his tank in a corner. He was still eating, though he didn't seem as excited about the food as before. He was also making lots of bubbles, I wonder if he isn't lonely/bored and wanting a mate. I also noticed his eyes look strange, almost cloudy. Sometimes it seems like he can't see his food - he only eats it when he bumps into it and realizes it's there. Today I noticed some flakiness to his skin :( not nearly as severe as my other fish, but almost like he scraped himself on something across the top of his body. I also don't know if I'm seeing things but he looks like he has a mild case of fin rot - his fins don't seem shorter, but the ends look sharper and darker in a way, and more separate like there are more little "points" at the end of the fin.
He is also in a 1 gal tank with a lid. There's some gravel in the bottom, 2 plastic plants and a little plastic mermaid in the middle. There's no heater (but I live in South America and it's pretty hot here right now) and no filter. I do a full water change every other day, and put dechlorinator in the water.
* Also just noticed something when I went to get the dechlorinator to find out the name. It says 1 drop per liter, and the petshop guy told me 4 drops for 2 liters. Could excess dechlorinator have anything to do with it??
I'll try to post pictures if I can. Please help, I don't want to lose my other betta