sorry for the sloppy example but i hope i get my point across.(its like 5 mins of work) but anyway, i don't know if you tried this before when you created the bump map in photoshop, but.... did you paint different shades of grey for different row of scales (circled areas 1 & 3)? because if you dont, you'll pobably get scales that seem to "cut into each other" due to the fact that all the scales are recognized as being the same height (rem: in real life, scales are not flat) and the only thing that varies are the dark lines that represent the areas between the scales (area 2). of course you'll end up with scales that look like they "cut each other"
hope i helped