What do you have him in? You can keep him in a larger storage bin till you find a tank you like. You can get a 3 or so gallon one for under $5 and then he can have a heater to keep him warm and more swimming room. I use them myself. I would much rather pay $7 for a 20 gallon storage bin then $40 for a glass tank. I'm cheap like that
Not the most attractive option, but for a short term, it's not so bad.
I got my 1st tank for a 2nd hand store - an aqueon mini bow 2.5 gallon. Thats how I ened up with my 1st betta. The idiots at petco ignored me so i helped myself to a betta. Sadly, I had no idea how to care for it
live and learn, I guess
I can't really tell from the pic but I think that is his normal coloring. He may be a butterfly as mentioned and some bettas just have odd color patterns. Keep an eye on him to make sure there are no behavior changes or physical changes like clamped fins, ect. The thing with such a small living space is ammonia will build up fast in a .5 gallon and that can cause all sorts of problems from ammonia burns, compromised immune systems and ammonia posioning which will lead to death hence the reason why I suggest getting a larger storage bin till you find a tank. Ammonia can burn holes in the fins. Are the fins turning transparent or are holes appearing? DId he have holes before? New fin growth starts out as transparent as well. I think, as of right now, it's just his coloring though.
oh, he could have the marble gene which can cause color changes..not sure it makes them transparent though. I think that's called a cellophane