please help my fish has fin rot
My fish has fin rot. I have been looking up all this information latley. My fishes name is kirby I was walking in walmart and I saw the poor guy in really bad water so I rescued him he has a two gallon tank it had a filter but it complelty destored his bubble nest so I took it out. His fins are black and ripped I got silk pants I change his water every two weeks. I got betta fix with no luck I bought him a heater so his water is at a constant 77-79 degrees I put the auqarium salt in with water conditioner I recently just went to a fish store named fish for u which they specialize in fresh water fish and got this medicine named tetracyclane. This is just my first time owning a fish and I am trying my hardest to make him better but all the information I get from the internet is all different is there anything else I could be doing?!?! And also how do you know when the fin rot is cured? I am just really confused and any information would be really helpful I just dont want him to die. :( also if anyone could tell me what type of filter I should get would be very much appreciated I had a whisper filter that came with the tank and I read on the internet that if I dont have one that I can control the settings it could have to much current and I was also noticing that his bubble nest were getting destroyed and that he was getting pushed around alot. So is an under ground gravel a better one for him? Please any info will help!