Aquaponics? I Just Want To Raise Some Fish
By Greg Peterson
For whatever reason when I came into this world I was very fascinated with fish. I liked pretty much every kind of fish imaginable and by the time I was 12 I had a paper route to make money and a nice selection of fish aquaria that I spent it on. I played with freshwater and saltwater aquariums, and by the time I was 15 I was regularly hanging around the ponds at the local fish store and cleaning people’s fishponds around Phoenix. Oh yes, I liked mucking out the bottom of long-forgotten fishponds.
Then it hit me that we could actually grow fish for food, so I started growing my own fish to eat. By 1979 I was working with others to design and build backyard aquaculture systems and convert people’s pools into aquaculture ponds. The thought of combining aquaculture and hydroponics crossed my mind – in fact I spent some time down at the Environmental Research Lab in Tucson, AZ where in the late 70s they were experimenting with this notion. I even went as far as building a simple aquaponic system in 1981 before becoming distracted by another project.
So let’s begin with a description of what it is:
Hydroponics is a process of growing plants using a mineral solution rather than soil. Typically, there is a basin of water and nutrient solution, which is periodically pumped over the roots to keep them nourished and hydrated.
Aquaculture is the farming of aquatic animals and plants. These can include fish, crustaceans and mollusks as well as a wide array of aquatic plants.
Aquaponics is a combination of both, using the fish wastewater to nourish the plants and the plants to purify the water in a symbiotic relationship.
An aquaponic system can be as simple as a fish aquarium with floating plants on the surface or as extensive as recreating your entire swimming pool into what Dennis McClung has created with his GardenPool concept. If you haven’t checked it out yet, the Garden Pool is one of the most brilliant pieces of urban reuse that I have ever seen.
A few years ago, I wrote a book called Grow Wherever You Go! As many of you know, I am a storyteller and I feel like the real life stories of others are a great way to inspire. So, at the end of the book I included some real-life stories about what others have done. I reached out to the planet and made a request for cool stories and Matt Johnson responded with his aquaponics story below.
There are many ways we can garden and grow our own food and aquaponics is just one of them. What is your way of contributing to the local food economy and growing food for your family?
Balcony Fish Farming
By Matt Johnson
When I moved into my condo three years ago in Kakaako, Hawaii, everything was great. I had easy access to a pool, hot tub, gym, mini-marts, bars, and the beach. Who could ask for anything more? Well, I decided that these modern conveniences were not enough and, in fact, I did need more. More green, more life, more non-concrete creations. A fortunate part of my living situation is that my condominium has a 400-square-foot patio. I decided to use this space to try my hand at urban farming with the goal of growing an entire meal just 20 feet from my kitchen. I am happily a carnivore, so I knew that in order to make a meal that I would truly enjoy I would need to have some type of meat. Chicken, beef, pork, and goat were out the question, even though I did think about it. However, there was no way to get around the condo by-laws that stated “no farm animals.” I decided fish was my only option. I also wanted greens to make a salad. So, with my end goal of a dinner of fish and salad in mind, I decided aquaponics was exactly what I needed.
As defined by Wikipedia, aquaponics is “the symbiotic cultivation of plants and aquatic animals in a recirculating environment.” Basically, it’s combining hydroponics with aquaculture in a closed-loop system that uses the fish-fertilized water to fertilize the plants. The plants then filter the water, which is deposited back into the fish tank.
Fortunately, my business allows me to work with all different types of farmers on Oahu; luckily, one of them is an aquaculture expert and another grows hydroponic lettuce. Both were willing to help me along the way. I found someone who was going out of business and was able to pick up a couple of 60-gallon fish tanks for $50 each. Granted, you could use something as simple as a five-gallon bucket, but I wanted something bigger. Next, I took hydroponic growing tubes and put them above the fish tanks, pointing down so that water flowing through the tubes would pass over the roots and fall in to the tanks at the end. The third part of the system is the sump tank, located underneath the fish tanks. As water enters the fish tank from the hydroponic growing tubes above, it causes the water to overflow into a three-foot-long pipe located at the middle of the tank. The pipe gravity feeds the water to a sump tank located underneath the fish tanks. In the sump tank there is a 1.5 HP (Hayward Pump) water fountain pump that shoots the water up through a hose four feet where it connects to one half-inch PVC pipe. The pipe distributes water to each of the hydroponic tubes through skinny straws. This completes the closed loop system.
After I finished building the tank stands out of four-by-fours and plywood (total cost of $50), it was time to find some fish.
Tilapia is the most commonly used fish due to its ease of raising. I started with six per tank that I harvested from a friend’s pond in Hawaii Kai, 20 minutes from downtown Honolulu. When putting fish into your tanks you need to make sure you have enough fish to create enough nutrients, but also not so many that the water becomes toxic to the fish. A rule of thumb to try to follow is two pounds of fish per cubic foot of water.
Another factor to consider is aeration, which helps the fish with breathing since they are enclosed in a relatively small area. I use an air pump that allows me to attach two hoses, one for each tank. I attached an air-stone to each hose and then dropped it into each tank. To propagate the seeds, I use a sponge-like medium, insert seeds into the growing medium, add water and in a few days, I have baby Swiss chard.
To date, I have successfully grown manoa lettuce, mesculin, Swiss chard, kale, parsley, and arugula. Within sixty days, most of the different types of lettuce are ready to harvest. Depending on the amount of feed given to the tilapia, the fish can be ready to harvest in 3-6 months.
After about three months of trial and error — lettuce dying because of not enough water and a few tilapia dying because they jumped out of the tank — my dream of eating an entire meal that had been grown on my balcony came to fruition. I harvested two heads of butter lettuce, some Swiss chard, and caught two tilapia. Before cooking the fish, they spent a few hours in clean water to help rinse them out before cleaning. I rolled the filets in flour and threw them in a hot pan with butter. The lettuce was rinsed and I added yellow-pear tomatoes that I harvested from a recycled bath tub that I use to grow various produce. My girlfriend brought over some wine and we had an enjoyable dinner for two.