Just got some in at our local BPS...I have had success with watermelon and green pumpkin during the day..but not much luck at nite with them..has anyone used the black ones at nite with any success?

Nope, Im same as you.  Watermelon and Green pumpkin.    Just pulled a 5lber with the green pumpkin last week. 

I keep three colors on of the Fat Ikas on hand at all times - Green Pumpkin, Dark Pumpkin (brown/orange), and Black & Blue.

They all catch fish...  I throw the black and blue in murky water all the time.  I don't night fish, but I can't see why it wouldn't work then.

Don't want to hijack but I keep seeing these things and have never tried them. What makes them fall backwards and what do they imitate?

rig them weightless with an offset EWG worm hook with the skirt on top.

they imitate easy prey

7.49 lbs on a Fat Ika

http://www.bassresource.com/bass-fishing-videos/lake-guntersville-2012.html