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Fish, Plants, and a Lesson in Sustainability

  At Baltimore Polytechnic high school, water gurgles through a series of 500 gallon tanks filled with fish.   The fat, foot-long tilapia produce waste that fertilizes basil and cabbage sprouts growing in pots suspended in the water. The plants help to filter the water and make it clean enough to recycle back into the fish tanks.

This is aquaponics: a combination of aquaculture (or fish farming), and hydroponics (the cultivation of plants in water).  

A growing number of systems like this are being built around the world as a way produce lots of food in a small space – with none of the water pollution caused by conventional fish farms.

What is most remarkable about this aquaponics system is that it wasn’t constructed by environmental engineers, but by high school kids – in their own free time, after school.

“Everything is self-sustaining, everything gets filtered,” said Eddie Caceros, a 17-year-old Junior from the Hampden neighborhood of Baltimore, who was part of a team that built the aquaponics system.  “There is nothing that goes back into the environment that is bad.” 

Caceros and his classmates spoke to guests during a recent open house at the school to show off the aquaponics  project.

 “I had never expected that I would be in here every day after school, till six o’clock, just adding onto these tanks every day, running into problems, but not giving up,” Caceros said.  “That was one of the  things – we just never stopped trying.  I can’t tell you how many times there was leaks in these tanks and people were discouraged. Everybody just kind of had to pick it up and keep moving.... It’s like a little family in here.”

This fish farm is also is also unusual in that it is highly computerized.

Rob Friedman, a senior and one of the project’s leaders, said: “Our specific aquaponics project is cool because we have each level that is important for an aquaponics lab monitored by microcomputers. And each one will measure the values that are important for an aquaponics lab, such as Ph and temperature. We graph those over time. And we have it set up so that our main computer can tell if the levels go out of the safe range and it will alert us and someone can come in and save the fish.”

Next to the four squat water tanks full of tilapia is a flat and wide water table with foam rafts floating in it and tiny pots with basil and cabbage plants. Overhead are LED and solar vapor lamps that provide light for the plants.  The students are comparing which type of light makes the plants grow faster.

Jeff Reeser, who teaches environmental science at Baltimore Polytechnic Institute, said the school will soon install a renewable energy system to power these lights and others at the school.

 “We’re getting a solar panel put in our parking lot which will actually power all of this,” Reeser said.  “The goal is zero carbon footprint for this whole system.”

The benefit to promoting systems like this around the world is that they reduce pressure on wild fish populations, which are being overharvested in many waterways.

Reeser talks about this in his class.

“In AP environmental science, we talk about sustainability. We talk about how the world’s oceans are going to be depleted if we keep taking and taking,” Reeser said.  “This will provide food and protein for a closed system.  You don’t have to go collect fish. You can raise your own fish in your own house.”

And what will happen to these particular fish?

 “We are going to make fish tacos at the end of the year,” Reeser said.

Sustainable tacos.  Food for the mind.

Tom Pelton, a national award-winning environmental journalist, has hosted "The Environment in Focus" since 2007. He also works as director of communications for the Environmental Integrity Project, a non-profit organization dedicated to holding polluters and governments accountable to protect public health. From 1997 until 2008, he was a journalist for The Baltimore Sun, where he was twice named one of the best environmental reporters in America by the Society of Environmental Journalists.