have a sweet mellow betta in a 30 g with 8 cories. Well, long story short now I have four cories and all are sick. One hour ago I had six healthy ones, now I have four. (Woke up to find two dead) please read Please Help! for more details. Amywhoo, this post is about my betta I love him so much. He is a marble rose tail. Well, I noticed his colors were dull and couple hours later, I saw the roots of his tail grey and rotting. What? An hour before he was dull but fine. Anything to do with cories? Pics below. Please help him. He is the fav of my bettas and I don’t want to loose him. Thanks in advance. Quick question: Would bettas act differently when marbling?