I bought him at the fish store as a julii cory, though I knew at the first sight he wasn't a julii (and their other "julii" were in fact C. Gomezi :) ). He's much smaller than my old cories, so I'd say he is a juvenile. If the fin spots appear later, that would explain a lot. Thanks for your answer ...

Looks like an elegans to me, but has no spots on his fins...