I had a l.m.b., it didn't care for store bought foods, barely gave them a second look. Try to mimic what it would consume in the wild, (i.e. insects, larva, minnows, crayfish...) Half the food you can catch in your own backyard. Keep the diet variable, change it up often and in little time it'll be huge. Mine was small enough to be transferred from the river in a Gatorade bottle and in 9 months it was over 12". It will grow a lot faster if you keep the water heated above 65F.