In nature, bacteria break down animal waste and decomposing matter allowing plants to use the nutrients. An aquaponic system also relies on these bacteria. Fish raised in a tank produce waste in the form of ammonia. This waste eventually becomes toxic to the fish if not removed from the system. For aquaponics, the hydroponic bed is filled with gravel or other similar media that provides plenty of surface area for bacteria to grow. It also provides physical support for the plants. By passing the water from the fish tank through the hydroponic bed, the bacteria break down the ammonia into nitrates that the plants use for growth. The ammonia-free water can then be returned to the fish tank and the process repeated.

Combining the methods offers several advantages over either one alone. Hydroponics doesn't require soil, but it can use significant amounts of water. By combining it with aquaculture, the water is conserved and re-used. Few or no additional fertilizers are needed as the fish waste is converted to organic fertilizer for the plants. In terms of aquaculture, since the fish waste is broken down naturally, there is no waste to be disposed of. Depending on the plants being grown, fish food is often the only thing that needs to be added regularly to the system.

Aquaponic systems can be almost any size, from small aquariums and grow beds to full scale commercial operations with large tanks and greenhouses. With the slow economy, individual homeowners are becoming more interested in simple systems that can be built to raise fish and vegetables for their family. While the demonstration system at the Escambia County UF-IFAS Extension office in the picture is a kit, aquaponics can be done with almost any containers that can hold water. People have used barrels, horse troughs, old bathtubs, PVC pipe, and ponds/tanks dug into the ground.

In Florida, the most common fish raised in homeowner systems are catfish, bluegill, sunfish, perch, and bass. Tilapia, while an excellent fish for these systems, is only permitted for commercial production in Florida. Leafy green plants including lettuce, collards, and herbs grow very well in simple aquaponic systems and local homeowners have also grown tomatoes, strawberries, turnips, and other crops successfully.

If you are interested in learning more about aquaponics, contact Andrew Diller or your local Extension Office for more information.