My beta used to be bright red. He is now almost all white with black spots. The spots aren't protruding or anything. He just looks like a beta with natural spotted coloring. However I know this was not his original color. What is happening?

So I have an 8 Gal Nano Cube for my little guy. Plants, filters, heaters, LEDS, the whole 9 yards. But the very ends of his tail fin is getting a little ripped, even though there is nothing that could catch it? He also has some black pigments....his is a white opalescent fish so it is really...