I have my rays on a diet of pellets and gelled diet. Seasonally I mix in smelt that I net from Lake Superior. Each time it rains I pick nightcrawlers. I buy shrimp once each month.
I have four adult rays and three juveniles.
Pellets: Buy 50lbs, twice a year @$0.72/lb.. Shelf life 6 mo. Frozen 9 mo.
Gelled: Buy 10 kg, twice a year @$26/kg. Shelf life 6 mo. Gelled, frozen, 9 mo..
Smelt: Net 50lbs once a year. Feed whole, unfrozen smelt intermittently.
Crawlers: Whenever it rains I pluck 'em till my back is sore. Usually a quart at a time. Fed to rays almost constantly until gone. (next rain, repeat).
Shrimp: Frozen, farm raised. Market price. Fed to rays sparingly over the corse of each month as a supplement.
Get a chest freezer and take advantage of bulk purchases. The pellets I feed come in a 50lb bag. I vacuum seal 1lb batches and freeze. Gel and smelt much the same. Immediate freezing helps to extend the life of the food.
There are some fantastic reads if you search this forum. Oddball and Miles have published a few good findings.
Respectfully,
FireMedic.