While in my last year of university, I became obsessed with the idea of having my own micro aquaponics ecosystem. Then, in a moment of weakness, I bought fifteen tilapia fry on eBay.

The Beginning

I was introduced to aquaponics by my neighbor, Jed. Aquaponics fascinated me because it is a miniature ecosystem, with its own nutrient cycle.

To those unfamiliar, an aquaponics system combines two high-density farming techniques: aquaculture and hydroponics. Aquaculture is raising fish, and hydroponics is growing plants with nutrient-rich water instead of soil. In aquaponics, the basic idea is:

  1. the farmer feeds the fish
  2. the dirty fish water feeds the plants
  3. the fish and plants feed the farmer

In some ways, an aquaponics system is similar to the famous Biosphere 2 experiment. Jed was eager to give hydroponics a try, and suggested we give it a go together.

One day, while walking home, I spotted a couple small glass aquariums someone left on the side of the road. I carried them home (with the owner’s blessing) and set them on Jed’s desk. It was a nice warm summer evening and several beers later, I found myself on eBay searching for fish. Turns out, there are people on eBay who will mail you live fish. I woke up to this email:

Your order has been sent Monday. 2 day priority. I will have tracking listed. Be watching for your fish, so they are not left outside long after delivered. To hot to cold. Also just wanted you to be aware of common mistakes. Don’t put in with other bigger fish or they will be eaten. Make sure intake/filter is small enough that they don’t get sucked in or they will die. This may seem obvious, but it has happened to customers before. Just want to protect your investment the best I can. You will want to acclimate the fish 20 min. In bag in tank when they arrive, just to help adjust them to temp. change. Feed them crushed flake food. Any other questions, or problems please ask. Thanks, Brad

The fry in their first tank. There is a sponge to keep them from going through the water pump.

The Girls

Jed was thrilled, of course. The fish stayed on his desk initially, and in short order he took to calling them his “girls”. The “girls” were blue tilapia, which according to my research were a pretty hardy bunch. This turned out to be true- all 15 that I bought survived and thrived despite my many mistakes in caring for them.

The fish continued to grow quickly. Up to this point, they were merely decorative, but the farmers were getting hungry. Below is a photo of the fish once they were first moved to a larger tank in my basement. At this point they are about five times larger than how they arrived. Shortly after this photo was taken, I converted our aquarium into a hydroponics system.

The finger-sized fish in a full-size tank.

The Lettuce

There are many techniques to grow plants without soil. One of the easiest ones is the floating bed approach. The plants are embedded into a floating structure and their roots are allowed to dangle into the nutrient-laden water below.

Below is a sketch of a basic setup. The water from the fish tank is cycled though the floating bed, flowing in from the right and exiting on the left.

Hand sketch of a floating bed for growing lettuce

I chose to plant lettuce in my basement. While not as valuable as other greens that may be found growing in a basement, lettuce has the advantage of growing really well on a floating bed setup and is unquestionably legal to posses. The newly germinated and planted lettuce plants are pictured below.

Newly germinated lettuce planted in a floating bed.

After a few weeks, the lettuce was really growing nicely, as shown in the next photo.

Lettuce half-way to full size.

I don’t have a picture of the fully grown lettuce, but it was very similar to what you’d see in a grocery store and I got a few salads out of it.

When the fish were full size, we made fish tacos. They were almost like pets at this point, so it was a bit sad.

Conclusion

Ultimately this project was far from cost-effective, but it was a fun and educational distraction from university. Additionally a lot of people came over to see it, so it had some value as a talking point. I should also give credit to some of the people in addition to Jed who helped me out along the way: Prof. De Rooy for lending me the large tanks, Julie for helping me transport them, and my housemates for letting me take over part of the basement for most of the year.

2022 Update

While in Singapore, I spotted an aquaponics setup very similar to the one I made. Of course, unlike my fish, these fish do not need to be kept under a blanket most of the time…

Instead of an aquarium tank, the fish are in a dark plastic tub that makes them hard to see.
The lettuce, in a floating bed identical to the one I made. IP infringement?
More lettuce, using a different strategy with the roots mostly in the hollow plastic pipe. I am curious to know which strategy grows better.