The black box does not attract fish, it limits the detraction from the electrical currents downrigger cables cause going through the water. A lot of commecial trollers use them, but then again they are fishing up to 6 cables at 50 fathoms and trolling up to 3.5 kts.

I have never used a black box and catch plenty of fish. Personally, I think it is just a hoax to get a bunch of superstitious fisherman to spend even more money on fishing tackle. Thats just my two cents, for what it is worth.