I have had a 5 1/2 inch Black Ghost Knife Fish for a few days, and was wondering how much to feed it. Lfs said only as much as the size of its eye per sitting. I had a hard time with that one. The research that I have done tells me that I should feed it much more. Right now he gets just under 1/2 cube of frozen blood worms a day and a small pinch of freeze dried brine shrimp. Is this too much or too little?