BCC students grow lettuce with the help of fish

BCC students grow lettuce with the help of fish

Image Credit: Scott Daniels

Buckeye Career Center natural resources instructor John Oliver has converted a section of greenhouses at the school into an ongoing demonstration of a closed system in which thousands of fish provide the nutrients to grow rows of lettuce. The results are surprising for anyone accustomed to traditional growing methods.

The lettuce is grown without using soil, and the process uses the fish to produce what the plants need. Students are given specific responsibilities for keeping the many large plastic tanks filled with fish.

Feeding the fish, all varieties of tilapia, provides a bit of entertainment each day. “The fish know when they see a human hand overhead, they’re about to be fed,” Oliver said as the students dipped containers of pellets out of a bin. As the food-wielding hands hovered over the water, the tanks began to bubble with the thrashing of fins below.

Once the food was released, the water churned briefly as the hungry fish fought to get their fill. “You have to be a little careful,” Oliver said. “They’ll go after your hand like that too if you put it in the water.”

The system yields results as waste from the tanks is piped to the waiting lettuce beds. “We planted those just two weeks ago,” Oliver said. “And you can see we’ve already been able to harvest some of it.”

The romaine lettuce had already begun to reach a mature size. To prove the lettuce isn’t an outlier among plants in the success story, Oliver indicated a small section of the greenhouse where a half-dozen date palm trees stood at nearly 3 feet high.

“We just planted those this school year,” he said, leading the way to another room of the greenhouse that utilizes more traditional growing methods.

“By comparison,” Oliver said, ”these four date palms have been raised here in a standard greenhouse — in soil with standard fertilizer.”

The second set of palms stood at barely a foot tall.

The excess fish waste is popular with Buckeye Career Center staff, who are grateful to use such a potent fertilizer on their home gardens.

“You can’t just put this on your plants, or it will burn them,” Oliver said as he drew off a gallon of black sludge. “You have to take this and dilute it.”

The students are caring for a large amount of aquatic life, which has led to educational opportunities. “We raise about 100,000 tilapia every year,” Oliver said. "We put 1,000 fingerlings into our pond in the spring as a start for the following year. By the time school starts, we have more than 100,000 fish ready to go."

The program has been in place for several years, enough for the classes to observe distinct genetic mutations.

“We found that every once in a while, we would get a purple color variation,” Oliver said. “Eventually, we had enough diversity to put them together.”

All of the resulting offspring are housed in a single, isolated tank, making for thousands of examples of the rare coloring. “This is the only tank of tilapia with this purple coloring variant on the planet,” Oliver said.

At the end of the school year, the fish go into the ponds of homeowners, and the process begins anew. “We also have a fish fry for the students with fish that are big enough to eat. Some of them will reach 3 or 4 pounds each,” Oliver said.

The program has proved so popular it has attracted students from outside the school’s traditional range. “They learn a lot about this kind of plant culture. We effectively have a self-contained wastewater treatment plant here. It also helps to teach responsibility and sustainable farming and fish culture,” Oliver said.

Buckeye Career Center is at 45 University Drive NE in New Philadelphia.