Red light, similar to the blue rope light, might be a better option. Fish don't see as well in the red spectrum, so most don't even notice it and won't panic when it comes on. I will allo you to see the fish moving around fairly well. If the fish react, it's a pretty good indicator that they do in fact detect the light.
Comparing humans under black light is really not fair--humans can blink, while fish can not.
Comparing humans under black light is really not fair--humans can blink, while fish can not.