I'm doing the same thing. I recommend you do a quick search on hydroponics and aquaponics. You'll find plenty of ideas and best practices. You'll want to engineer a way to cover it and protect it from birds and other critters while still allowing insects for veggies that need pollination. Growing baskets are inexpensive upgrades. Soil-less ceramic medium can be used.
It's also a great "add" for a pond that has high nutrient load. That's what got me started on planted islands myself.
Dam'd Waters Farm
2/3 ac dam'd stream pond
BG, HBG, RES, LMB, YP