I came into my room tonight to find my fish Jasper is missing some of his tail! The edge looks all raggedy, with the thin parts of his tail seemingly torn off and the thicker lines of his tail still, for the most part, in tact. I really don't think he's ripped it on anything...I have a plastic cup in my tank with no rough edges, a silk plant, and a filter, which Jasper has a liking to swim behind, but I see no rough edges...the filter is shaped like a cylinder. I have heard of bettas "blowing a fin," but I'm not entirely sure what that means, and if that's what's happened to Jasper. I know that fin rot is at stake, and will be taking measures to make sure he does not get it.
Also, if someone could tell me how to post pictures if at all possible? So I can give a visual? :)