By Kimberly Griffin
I have a couple confessions.
First: I love systems, especially closed-loop, self-sustaining systems. I geek out at the word “compost”. And I get really excited when it comes to greywater systems. It’s safe to say that I love systems that focus on alleviating stresses on our environment by embracing best practices for utilizing and re-utilizing essential yet limited resources.
Second: I love to eat fish. I grew up in Florida and my current residence in Vermont is truly the furthest I have ever lived from an ocean. I most recently lived in the White Mountains of New Hampshire where I ran a CSA-style seafood club alongside a vegetable CSA. It was a joy to provide folks with fresh, local, organic vegetables and offer fresh, local, sustainably-caught wild seafood. Members received weekly portions of the ocean’s harvest from a fishing operation out of Portland, Maine. The variety of seafood followed the seasons of the water. When I was planning the move to Rutland, my friends in Portland asked if I would continue my mongering in Vermont. My first thought was “sure, once fish grow legs and move inland”. My next thought was “aquaponics”.
Aquaponics is a system of growing food that brings together aquaculture – raising aquatic animals – and hydroponics – growing plants in water. There are skeptical opinions on both. Farm-raised fish have gotten a bum rap thanks to some ill-followed practices in segregating the ‘domesticated’ version from the wild in oceanic pastures. Similarly, soilless plant production has raised suspicions among many, due mainly to dependencies on synthetic nutrients that are injected into the water to make up for the lack of naturally occurring soil-borne bacteria and nutrients. Aquaponics, when done correctly, strives to mitigate these issues, while taking efforts a few steps further. Creating a conscientious aquaponic system can actually regenerate environments, rejuvenate economies, help to close some of the input-dependent food production/consumption cycles, and be vastly educational.
My interest in aquaponic systems recently took me to Saratoga for the annual NOFA NY winter conference. Scott Kellogg, from the Radix Center in Albany, lead a three-hour session on the topic.
Here’s some science: Fish waste is high in ammonium compounds (NH4+). Good bacteria, essential to all life forms, break down these compounds into nitrites (NO2) and nitrates (NO3). Plants, both terrestrial and aquatic, need nitrates to grow.
Picture your basic home fish tank. You’ve got Goldie, Flipper and Jaws all swimming around, hiding in castles and brushing past small plastic kelp. Aside from the tank itself and the water, your major system components are the filter and the bubbler. The filter, usually some sort of synthetic material, “scrubs” the water and collects bad bacteria to keep the water quality at a healthy level for your aquatic friends. The bubbler makes the oxygen in the water more accessible, allowing the fish to breathe.
In an aquaponics system, Goldie, Flipper and Jaws get their very own tank, which can be as small as a five gallon bucket and as large as an olympic-sized pool. A grow bed of plant life resides above the fish tank, housing plants ranging from the aquatic, like watercress, to the terrestrial, like lettuce. Inside the fish tank there is a pump. Nutrient-filled water is pumped up and out of the tank and into the grow bed. The plants and bacteria act together to filter the water. As the water flows through the grow bed, it is not only filtered, but it is aerated. Gravity plays its hand in letting the clean water fall back into the tank, providing fresh water and air to the fish.
Plants grown within an aquaponic system can be used for a range of consumption. Human pallets can be accommodated with lettuce, Swiss chard, and watercress. Livestock such as chickens love water hyacinth. Azolla is a fantastic addition to the compost pile and pitcher plants are beautiful ornamentals. Appropriate fish varieties range from the plate-friendly perch to the ornamental koi. Possibilities are endless given the space, desired uses, and willingness to experiment. For more information, check out the Radix Center at radixcenter.org. And Sylvia Bernstein recently published Aquaponic Gardening: A Step-By-Step Guide To Raising Vegetables And Fish Together.
By creating a system in which a waste product is consumed, turned into a nutrient, consumed, then turned back into a waste product to be again consumed, you are closing the loop and creating an interdependent, regenerating cycle. It’s beautiful! There are, however, some pieces that need to be improved upon. Fish eat a multitude of foods and diets vary from fish to fish. That means that in some cases, you can grow your fish food, but in most cases, you have to buy it. Also, because you are essentially creating an ecosystem, regulation is important. That means occasionally relying on outside resources for heat and light. Aquaponics is not the silver-bullet solution to providing alternative fish sources. But it might offer a local, temporary ecological vacation for the oceans, or a fascinating means to teaching folks about nutrients cycles and environmental regenerative systems.
Kimberly Griffin is currently working with the College of Saint Joseph to develop an on-campus farm for educational and edible use. She can be reached at firstname.lastname@example.org.
Originally published in the Rutland Herald.