I dunno.. my western painted kind of started to fade a few years ago & then I read that lack of vitamin A can cause fading. I put him on a liquid reptile vitamin once a week & he really started to color up. He's not one who's interested enough in veggies to get him eating alot of veggies high in A.
Then of course I couldn't find that vitamin anymore & so he started to fade again.
A year or so ago I put him on Jurrassi brand aquatic turtle pellets. He still gets a lot of live food but when he gets pellets he gets that brand.
I did it because I liked the idea that it has no soy which a lot of people now say interferes with calcium absorption. It also doesn't have any dye in it.
His color brightened up again with that brand.
You may just need to try that pellet or find other foods that are naturally higher in vitamin A. I wouldn't just give vitamin A because it can build up to be toxic but giving it naturally with foods that are high in it is different.
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PHRatz