Aquaponics is the integration of aquaculture (fishkeeping) and hydroponic (soilless) plant growth techniques. It requires no soil and no chemicals to produce a vast and large amount of fish, fruits and vegetables in a very small space. Fish produce amonia as waste. Bacteria convert that waste to nitrates used by the plants as the nutrient source. The water is recirculated to the fish clean and aerated. Water consumption is lower and plant density is usually at least twice that of soil based methods.
No pesticides can be used as they would kill bacteria and fish in the system. Food produced is thereby pesticide free. Travis Hughey is the inventer of the Barrel-Ponics method of aquaponics and the author of The Barrel-Ponics® Manual which is available as a free download from this website.
Below may be some other helpful information for your aquaponics system.
Manuals for Beginners