NASHUA – Leading up to this month’s program, Science Cafe NH organizer Dan Marcek wondered if the chosen topic – aquaponics – might just be one that lacks the power to draw in the crowds the cafe is so used to.

But not to worry – even the seemingly fringe
subject, which is essentially the marriage of aquaculture (raising fish) and hydroponics (soil-less gardening) brought a full house and the robust participation for which the monthly get-together is known.

And leave it to the science-minded to come up with the kind of questions and comments that leave even the uninitiated muttering, “wow … fascinating.”

“A lot more came than I thought would,” Marcek said afterward. “And what we liked best was there were so many new faces.”

From proper climate and light, breeds of fish, types of filters and the introduction of predatory spider mites to ward off pests, three individuals with varying, but similarly deep, knowledge of aquaponics and its cousin hydroponics covered most everything there is to know about the increasingly popular endeavor that many are adopting as a hobby.

Successful aquaponics starts with deciding what, and how many, plants you want to grow and matching that with the species of fish, said panelist Jessica Normand, a UNH-Manchester student majoring in biological sciences.

Anthony Eugenio, CEO of hydroponics and aquaponics specialty shop Green Harvest Hydroponics in Plaistow, told the group the easiest aquaponics system is the ebb and flow, or flood and drain, system that he recommends for beginners.

When it comes to populating the “garden” and choosing fish, “less is more,” Eugenio said. “Your plants are your filters. The whole idea is (to keep it) as natural as possible.”

While the premise of hydro- or aquaponics is pretty straightforward and easy for novices to digest, those who study and practice the processes can reel off plenty of finer points that they either learned or discovered by chance.

For instance, panelists agreed that roughly 75 degrees is the ideal environment for plants, and if inside, making sure light is sufficient is most important.

Outside, of course, is the sun – “the best light ever,” Eugenio quipped – and the best species of fish to use are ones that are most apt to eat anything, sort of a billy goat of the water world.

Too cold, panelist Mike Griffin cautioned, and nutrients don’t flow well, endangering the life of the fish and forcing the aquaponics hobbyist to start all over.

Stay away from bottom-feeders like catfish, Eugenio added.

As for plants, vegetables like kale, chard, lettuce, basil and most herbs, including mint leaves, and peppers and even tomatoes are Griffin’s top choices.

Asked about potatoes and carrots, Griffin suggested carrots could do well in a flood-and-drain system, but potatoes are still a wild card.

As for tomatoes, plan on introducing plenty of fish. “Tomatoes are nutrient hogs, they need a lot of food,” Eugenio added.

Normand, who is on something of a mission to boost the popularity and knowledge of aquaponics in the Northeast, presented earlier this year an independent study on the subject at the annual Undergraduate Research Conference.

“Yes, I have a love for aquaponics,” she said. “We’re trying to make it bigger up here.”

Hudson resident Justin West listened eagerly, alternating between asking questions and poring over notes he compiled.

The subject came up at an opportune time, he said. “I’m in the process now of building one,” he said of an aquaponics garden. “What I’m still not sure about is whether i can pull of (using) tilapia. Of the three main elements – plants, fish and bacteria – bacteria is really important,” West said. “You need the right kind.”

Griffin, who returned to his passion for farming and fish after 25 years in the construction field, began by adding a greenhouse onto the barn at his and wife Tracy’s home in New Boston. He started out big, filling a pair of 750-gallon former cattle troughs with water and fish, goldfish in one and fledgling tilapia in the other.

“It’s almost time now to harvest them,” Griffin said Wednesday of the grown tilapia. And people are lining up to grab their share.

“I’ve got calls from restaurants, farmers markets, older people…pretty much this whole harvest is already spoken for.

While he’d need permits to sell the fish, say, on a plate, not so for live tilapia, Griffin said. “I can sell them whole…I just put them in ice water for customers. It’s a whole lot better than cutting heads of in front of a lot of kids,” he said of the traditional method of preparing fish for sale.

For more information on aquaponics, see the website for Eugenio’s store, www.greenharvest
hydroponics.com, or search the term online.

Dean Shalhoup can be reached at 594-6443 or dshalhoup@nashuatelegraph.com. Also follow Shalhoup on Twitter (@Telegraph_DeanS).