Lots of people are doing this as a sustainable living model called aquaponics. Raising fast, edible fish in a large several hundred gallon stock tanks, etc like tilapia, perch, etc, then using the water from there to grow vegetables, herbs, etc and other edible plants, thus creating a self sustaining system that you can eat fish and veggies from. Fish breed, you get more fish, save/plant seeds from veggies, repeat, so maybe use your model to explain this to your class.
20g platy, , 2 x 10g shrimp, 3 x 20g shrimp, 7.5g shrimp and 1 great dane/mastiff puppy.
Sump Pimp #2
My Tanks and my shrimps