Aquaponics

1. Fish are fed and excrete ammonia-rich waste into the tank water
2. Water flows through a biofilter where nitrifying bacteria convert ammonia to nitrite and then nitrate
3. Nutrient-rich water is delivered to plant grow beds (media beds or floating rafts)
4. Plant roots take up nutrients and help filter the water further
5. Filtered water is returned to the fish tank, completing the recirculating loop

This nitrification process is the biological core of the system: without an established, healthy bacterial colony, ammonia can build up to levels harmful to fish.

Fish tank

Holds fish and receives their waste as the nutrient source for the system.

Biofilter

Provides surface area for nitrifying bacteria that convert fish waste into plant-available nutrients.

Grow bed

The plant-growing area, using media, floating rafts, or other soilless techniques.

Sump and pump

Circulate water between the fish tank, biofilter, and grow beds to maintain the loop.

Crop and fish choices depend on matching nutrient supply and demand and on water-temperature tolerance. Leafy greens are common because their nutrient needs are often well matched to what fish waste supplies; heavier-feeding crops may need supplemental nutrients such as potassium or iron, since fish waste alone does not always meet every crop's full requirement.

• Recirculating design can use water more efficiently than separate soil-based production and pond aquaculture
• Combines two outputs (fish and plants) from a single nutrient and water cycle
• Can be operated in controlled indoor or greenhouse environments year-round

• Requires continuous power for aeration and circulation; equipment failure can quickly harm both fish and plants
• Balancing fish stocking, feed rate, and plant nutrient demand requires ongoing monitoring and skill
• Not all crops or nutrient needs are well matched to fish-waste-derived nutrients without supplementation

Aquaponics is used in controlled-environment and urban agriculture, research settings, education, and a number of small commercial operations. It generally remains a niche approach relative to conventional soil-based and standalone hydroponic production.