Could have been me, as I remember mentioning this in one or two threads where members were having difficulty catching fast fish. Apparently if held motionless, fish do not see it, so it is easier to herd them into a stationary black net. I've used white, green, blue and black, and black has beeen easier.
No problem, doesn't matter who suggested. I must admit I was skeptical when I heard this, it was when I was looking for a new net and the fish store fellow said black because they can't see it unless it moves.