Aquaponics is a combination of growing fish (aquaculture) and hydroponics (growing plants without soil). Fish wastes are turned into plant nutrients and plant wastes are turned into fish nutrients.
Backyard fishfarming simplified is small scale aquaculture.
If you don’t have that much land for ponds, you can use other means of where to put your fishes, like big drums or tanks or even kiddie pools. Use whatever is available for you in your area and what you can afford.
Organic vegetables and fresh fishes right at your doorstep :).