Okay so I hope I am over reacting but today I looked at my Bettas before feeding and my white male Betta has a bright blood red section on his tail. He is a rose tail with perpetually torn fins no matter what I do to help him. He has clean water, cycled tank (0.0.10), no sharp object or plastic plants, his only decorations are smooth and his only plants are real plants. This is a 20L divided with 3 other male Bettas. His behavior has not changed but I concerned about his tail. I know Bettas change coloring throughout their life times but I have had his almost 6 months or more and he has ever had a change like this and this happened over night. Is this something I should treat? Bacterial? Any ideas.