Tilapia's pretty cheap than shrimps in our place, but ofcourse you'll get more meat with shrimps than tilapia, you won't probably gonna feed all of it in a whole serving, least you'll ended up with a 0.55 pounds of fish/shrimp meat for a week. I've got 8 bichirs and they don't even have the capacity to eat all of it, IMO I feed in variety so there will be no just tilapia for the whole week.