Betta fin problem?

Question

Fins   Hi Jaymie,

I contacted you a few weeks back about my betta getting a small case of fin rot which I am still treating. He is in the 20L heated tank and the water conditions are pristine with 0ppm of ammonia and nitrite and little nitrate. I have been doing 25% water changes every two days and adding in dissolved aquarium salt to the required amount. His fins were getting better but today I realised he has a very big triangular slit on his back fin which I have tried to take an image of, it doesn't show the size of it.

I am beginning to wonder if he is getting very stressed as he is able to see his reflection as we go into summer. The sun has changed angles so I try to keep the blinds shut. He is very active and being very much himself, I am just worried about his fins as I am doing all that I can do.

Could he be nipping his fins? I haven't seen him do it though. I am going to monitor him closely to make sure the fins don't get worse.

Also the temperature is rising to around 29C during the day as it is getting to around 30C outside. Could this be causing the problem?

Fish keeping is so stressful, I thought I was doing everything right and something so small has now turned out to be at least a months battle. The good news is that the 54L tank I am cycling for him is nearly done! Around three weeks left, and I believe that tank will improve his situation as it is much nicer and he loved being in it for the short period of time after the heater broke in the 20L

Answer
Alexander, I doubt he is nipping his own tail. You are doing too many water changes. You only need to do 25% changes once a week. Make sure the water going in is the same temperature as the water he is swimming in. He is still showing signs of fin rot. Are you only using salt to treat or are you using medication? The temperature is still good and will not cause anything to happen to their fins or tail. As I have stated before, male Betta's do not need nor do they like filters. This could cause them to stress and get ill.