I got my betta 2 weeks ago. His home is in a 3.5 gallon tank with a small heater keeping the tank fairly consistant at 78 degrees Fahrenheit. The tank came with a filter but after a couple days with it on I found the current was way too strong and my betta didn't like to swim around because whenever he got close it would push him around. So I turned it off. I changed about 20% of the water with treated water as instructed about 5 days ago. But lately I've noticed a few things. First, my betta doesn't swim around as much as he did in the first week, he just kinda floats there, usually balanced on a plant, not always right side up sometimes sort of on the side. On occasion he'll swim up and down the tank spastically in the same corner. And finally his fins are splitting a lot. His back fin has at least five splits through it.
I'm really worried about him. Can anyone give me any advice about what may be wrong and what I can do to promote the healing for him and possibly fix the problem?
Thanks! And my betta will thank you too!