Fish fin highlights: why all the blue?

[davidcalgary29]

Okay, here's today's dumb question: is there some evolutionary reason why so many species of fish have blue piping -- rather than some other colour -- on their fins? All my centropyge angels have it, as does my striped squirrelfish. I can only assume that it's some type of reproductive strategy, as visibility doesn't appear to change in different lighting. Then again, I'm not familiar with piscine ophthalmology, so perhaps they're definitely seeing something that I'm not. Thoughts?

 

[Spare time]

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