about $5/week but that's including my 3 bichirs as well. my parents buy shrimp and i breed my own earth worms in my shed so that doesn't cost me a thing. i buy big bags of massivore that last me a while, maybe 1 every few months.
Wow I feel I must be getting ripped off at the store with the cost of what the rest of you are spending. Smelts , tilapia, and most other things we mostly feed rays cost more around here than shrimp. In our town 2lbs of shrimp is $14. I guess my big eater is my castexi who eats just under half of what all 17 of the other rays eat.