Got this info from Glynn Barber of Redke, Indiana that builds and designs aquaponics systems and grows aquaponic plants for a living along with redclaws. Thought I'd pass it on. Thanks Glynn!
Regarding raft culture (DWC)
.25-.5 lbs. tilapia per gallon of water in fish tank equals 3/4 sq ft plants per pound.
3-11 lbs. leafy veggies per pound of fish.
12-25lbs fruiting plants per pound of fish.
Tomatoes 20-25 lbs because they are mostly water. Some good reading on the subject:
http://www.aquaponic.com.au/Fish%20t...t%20ratios.pdf