[Delphinus]

I'm fairly certain it's a BTA as well. The probability of BTA is about 95% and the probability of ritteri about 5%. At this size they can be hard to distinguish but it does look more BTA to me (just basing this on having looked at a LOT of both species over the years).

As for the bleaching, it's hard to say. They can lighten up, or darken up, in response to changes in light conditions and this can be as simple as it moving under an overhang or deeper into a crevasse and thus getting more or less light. It looks healthy to me, they derive far more nutrition from feeding than from photosynthesis anyhow (actually the energy they do get from photosynthesis tends to be more like carbs, high energy, quick release type stuff, like eating a candybar; but feeding tends to yield more slow-release protein type energy which is better for growth). I don't have any links handy to back this claim up offhand but the info is out there if you wanted to google on it. Point being though, that as long as it's eating and otherwise doing OK the specific hue isn't as important as other things.