I have a 10G tank with 6 Bloodfins in it. This morning I fed them with the usual flake food that I use. After I returned from class I happened to notice one of them swimming near the surface of the water. It's mouth was open and it appeared to have a piece of food jammed in it's mouth. Since then, the fish has lost almost all of it's color. Is it choking? Is there anything I can do to help it? Any help is appreciated.