Not only is it possible to farm fish and crops at the same time, it's beneficial. Aquaponics is a technique whereby the waste that builds up in fish tanks is used as fertilizer for hydroponically grown plants. The plants filter these nutrients out of the water, which can then be returned to the fish. Because this is a closed system that recycles water, it uses a lot less water than traditional farming methods. The fish-waste feeds the plants, which means no chemical fertilizers are needed. In fact, after the system is set up, the only thing that needs to be added is fish food, along with a little extra water to make up for evaporation. Aquaponics also doesn't use pesticides, since they would be detrimental to the fish, so the whole system is very environmentally friendly.
Aquaponic systems can be set up on a commercial scale, but they also can be built quite easily at home, providing you with healthy greens, herbs, fruits and vegetables and fish for eating (or just for pleasure). You'll need:
- A fish tank for your fish
- A hydroponic grow bed for your plants, with either gravel or clay to support the plants and help filter the water
- Tubing to transfer the water from the tank to the bed and back
- At least one pump to move the water from the fish to the plants; gravity can pull the water back to the fish tank
- An aquatic heater to maintain a water temperature appropriate for both the fish and plants
- A pH test kit; your water should be about 6.7 to 6.9
- You may need an aeration system to ensure there's enough oxygen in the water
Many types of fish can be used in aquaponics, such as bass, perch and trout. The most common is tilapia, which are know to thrive in aquaponic systems and are in high demand as an eating fish. Herbs, such as basil and watercress, and leafy greens like lettuce and spinach do well when grown this way. You can grow a variety of vegetables, such as cucumbers, peppers and tomatoes.