i have a 3 or 4 inch black ghost knife fish. he is so awesome, but when i moved him from a ten gallon to a 20 gallon long he stop feeding from my hand! i can hand feed him only at the surface. i feed him frozen blood worms but i want to mix his diet so i bought beef heart, but he wont eat the beef heart! is there a reason or way to get him to eat it?????? i keep trying every night