Fish+Plants=Sustainable Produce AND Sustainable Fish

There's hydroponics and there's aquaculture, but when the two farming methods merge together--Voila! Aquaponics is born. Aquaponics is the symbiotic cultivation of fish and plants, and I'm a little surprised it hasn't become a popular venture yet. There's high demand for fish, and increasingly for sustainable fish, as wild populations dwindle and farmed fish often wreak havoc on the environment. Aquaponics not only provides an alternative to the typically unsustainable fish farm, but also has the added benefit of supporting the production of sustainable vegetables and other plants. Seems like a great idea to me!

Aquaponics at its best works in a closed circuit system. The fish are raised in tanks of clean, fresh water. The fish waste accumulates, rich in nitrogen and other nutrients. Once a day or so, the water, and with it the waste, is flushed and replaced, so that the high nitrogen levels don't poison the fish. The fish wastewater is then added to hydroponic vegetable tanks. The plants take up the nutrients in the water, effectively filtering and cleaning the water. Theoretically the cleaned water could then be returned to the fish tanks and the process could start all over again, but in practice much of the water is sucked up by the plants, especially crops like lettuces, which are composed of about 98% water.

The idea behind aquaponics has been around for centuries though, and in many parts of Southeast Asia, fish are integrated into flooded rice paddies, feeding on farm waste and fertilizing the rice fields. But for whatever reason, more modern aquaponic farming operations have yet to catch on in most places. One of the reasons for this is that the initial investment in aquaponic equipment can run upwards of $50,000, which is a daunting figure for most farmers.

Still, aquaponics has a lot of potential for producing sustainable food. One of the most inspiring examples of truly sustainable aquaponics systems is up and running in an unassuming rural town in Maine. The sustainable beauty of Home Grown Aquaculture Engineering lies in two key factors. The first is that the farmers raise tilapia rather than other fresh water fish like trout. Not only is tilapia a very marketable fish these days, but it is unique in that tilapia give live birth, allowing Home Grown to build its own breed stock rather than relying on fingerlings from a hatchery that are prone to contaminates, like mercury. The second factor is that in addition to vegetables, Home Grown also grows hydroponic duckweed. Duckweed can be used as fish feed as well as for livestock feed, eliminating reliance on manufactured fish feed which is often made from other fish, corn, and other not-so-sustainable nutrient sources. Home Grown also produces their own biodiesel, which powers the green houses and fish tanks. All in all, it's a beautiful example of sustainable farming and fish.

It's not clear whether or not aquaponics works well on a very large commercial scale, but given the holistic nature of well planned and well managed aquaponics systems, like the operation that Home Grown has developed, it seems as though it is something worth exploring.

Photo Credit: CC BY 2.0