Nine goldfish, three fence posts and some scraps of PVC pipes might not sound like much of a combination.

Nine goldfish, three fence posts and some scraps of PVC pipes might not sound like much of a combination.

But in the hands of Tyler Franklin, these repurposed materials have helped convert an unused space in the Minnesota State University Moorhead greenhouse into an oasis brimming with life, the Forum of Fargo reported (

The senior ecology and evolution major has worked since the winter to build up an aquaponic system in the greenhouse on the roof of the Science Lab building.

A large tank on the floor holds nine goldfish that he feeds every few days. A pump on a timer draws water from the tank up into a pipe every couple hours, where it then travels through the three hollow fence posts that each have about 25 holes cut in the side and a small plant in each hole.

Franklin said the plants benefit from the fish waste, which acts as an organic fertilizer, while also filtering out the water and returning it cleaner to the fish. This process, combined with a careful balance of bacteria and a "biofilter" that uses tightly packed netting to further clean the water, gives the fish a safe place to live and adds more oxygen to the water while also producing a bumper crop of tomatoes, basil and other plants.

"It's that focus on ecology and life, and it's really a dynamic living system," he said.

Franklin said it's a combination of two techniques - aquaculture, the raising of fish, and hydroponics, a way of growing plants using nutrients in water without soil.

He said a friend suggested trying the technique in his backyard, but the region's climate forced the project indoors.

About the same time, Franklin got a part-time job taking care of the greenhouse at MSUM and ran his idea past advisers.

"They almost seemed a little reluctant at first," he said. "They didn't really know what I was going to do."

He made his first attempt at building the system over the winter break, finishing up a few weeks later. He built a second one in February and has since worked to add new features to improve the system - and make it "a bit more attractive" to sell the idea.

Biosciences professor Andrew Marry said Franklin was a student representative at a conference for MSUM and saw an aquaponic display at an airport, immediately noticing that system's error of using too many inefficient lights. He returned to campus with the hopes of building his own, and was awarded a student grant from a campus sustainability group to make his project "an undeniable, fantastic success."

"Tyler's system is of great value as an education tool for many classes taken for a number of majors at MSUM," Marry said. "This will provide a great many students with a fantastic practical working example of how an enclosed, sustainable agriculture system works."

Franklin said he has plenty of ideas to make his aquaponic garden even better, including finding a way of lifting water without an electric-powered pump or using solar power to make it green. He said it also would be possible to raise tilapia or other tasty fish in the system, rather than the inedible goldfish, to make it a two-way source of food.

But he said he's pleased with how it turned out, and said his goal all along has been to make it as eco-friendly as possible. Most of his project is built with found or recycled materials, whether it's the old fish tank and pipe scraps or repurposed lumber and buckets.

Even the goldfish are recycled - Franklin's fertilizer producers came from a MSUM professor who performs a surgery on the fish to test if they can smell a chemical cue. Normally, they're fed to a northern pike after the research.

"They were on what he calls 'death row,' so I gave them a place to live for now," he said.

Franklin said he's benefitted from the work, too. He said he was eating big salads of organic kale and beans and munching on a wide variety of tomatoes earlier this spring, even as his garden at home remained buried under several feet of snow.

But he said he hopes that this concept can help others realize the potential of a little space on their own rooftop and not just be seen as an academic research project. He said more aquaponic systems like this could help relieve the ecological stress of agriculture as farmers work to feed a growing population.

"I'm not doing anything groundbreaking at all," he said. "It's educating myself and sharing what I'm learning and showing people that it's not incredibly difficult. It takes a little bit of work, it takes a little bit of time, but you could spend your time sitting at home watching TV or you could spend your time trying to help yourself and trying to help your community."