does it matter what kind of fish or not? and can i just buy shrimp in bulk like at walmart? also my eclipse catfish arent eating the best, they pick up flakes occasionally but when i bought them they had big fat bellies. What can i feed them? the lfs said they fed them blood worms so i bought some they just dont really seem to interested. if i had to guess the eel is in the 6-7 inch mark if i had to guess