Hi all, I've had my betta for just under a week now, and I think he may have fin rot (I'll attach some pictures). When I brought him home the tips of his fins were black, but as his body is black I thought it might just be part of his colouring and kept an eye on it. He did also have a little twisting on some of his ventral fin tips. He's been eating fine and still seems to be active, swimming around with no issues. Yesterday I noticed a couple of the tips on his tail fin were bent. Does it look like fin rot? And if so, what would be the best way to treat it? I've read aquarium salts in small doses can help. In the meantime I'm keeping the light in his tank off in case its stress related. My ammonia and nitrites are 0, my nitrates are between 20 and 40. I've done two small water changes(20/25%) since putting him in because of the nitrate reading. Temperature is 24°. If you have any advice I'd be very grateful, if he is ill I want to be able to help him get better asap.