For the past two semesters I’ve been taking classes in aquaculture. I figure, I like fish and I like eating fish. I also happen to have a lot of un-academic knowledge about fish since I am fish expert at the store I’m at. I’ve read tons of books and have hands on experience with many, many different types of fish from white clouds and guppies to frontosas and arrowanas. BUT. During this class I was introduced to a concept called aquaponics. Prior to this I did know what it was and I had heard about it, but I had never tried it out myself despite the fact that I have a pond full of fish that could benefit from this. SO.
After a few lessons and tips from my instructor and classmate, as well as some hands on experience with a full system, I decided to make a small one myself. I don’t have a picture of it right now but I’ll upload one later. It’s balcony sized but very productive. I’m experimenting with different herbs and fruits and vegetables right now. I’ve got strawberries, blueberries, zucchinis, two types of tomato, basil, watercress, manoa lettuce, two types of thyme, lavender mint, pinapple mint, sage, spearmint, rosemary, some sort of lavender, green bell peppers, some type of sweet chili, sweet peas, a small palm tree sprout, some sort of weed with white flowers (it’s supposed to be decorative), a succulent, two types of orchid, and oregano. Some are doing too well and some aren’t that hot. One of the orchids I actually brought back to life with this system and it’s happily sprouting flowers.
But yes. The basic principle behinds this is to have some sort of marketable fish that you can sell in a large body of water. The fish water is pumped into the plants and the water drains out of the plants and back into the source. Simple right? And it works so well! Here’s why:
WARNING: SCIENCE CONTENT AHEAD!!
It all has to do with the nitrogen cycle. In the simplified version the nitrogen cycle starts with nitrogen in the soil which is then taken up by plants and converted into useable biological molecules such as amino acids, pyrimidines, and purines. Primary consumers, the herbivores, eat these plants and use the molecules for their own purposes. Many amino acids are glucogenic (can be converted to glucose) and when the herbivores metabolize their food, a lot of the amino acids and nucleic acids are digested and some of the nitrogen molecules are used for synthesizing other amino acids, but most of the nitrogen is taken out of the system and excreted in various unusable forms: ammonia, uric acid, and urea, depending on the animal we’re talking about. ANYWAY. When the nitrogen is excreted it returns back to the soil and is taken back up by plants. Uric acid and urea are then reconverted by bacteria into ammonia, then to nitrates and nitrites which are the versions of nitrogen that are usable by plants.
SO back to the fish. Fish excrete ammonia and in a ripe tank, Nitrobacter sp. converts the excreted ammonia to nitrites, then to nitrates. The nitrates naturally build up in the water and are used by algae. BUT if we divert this water to other, more useful and marketable plants, then THOSE plants benefit from the nitrogen rich water and they flourish. The clean water is then put back into the system and this prevents uncontrollable algae buildup and massive fish loss due to them poisoning themselves with their own waste. :C
END SCIENCE CONTENT
So. That being said. The ideal aquaponics system has both marketable fish and marketable plants benefitting from each other in one microcosm. As humans we can eat these fish and plants or sell them. It’s also a SUSTAINABLE way to have a vegetable garden of your own that produces enough fruits and vegetables to live on. (or at least supplement your diet) All your products can also be labelled as ORGANIC! omg buzz wordsss!! Anyway, the marketing is for large scale operations so I’ll focus on the small scale, personal aquaponics system.
If you don’t plan to have tanks full of tilapia or catfish then you’re probably going to have to use ornamental fish. I chose different types of goldfish to be my main poop producers since, well, they are very good at it. They are often placed amongst the dirtiest fish in the pet industry. So in my pond I have 3 koi, 1 lionhead goldfish, 6 feeder comets, and 18 baby koi. I also have in there about 10 mosquito fish (but they keep breeding) to keep mosquitos down, 1 whiptail catfish, and 1 sailfin pleco to keep down algae and sludge. The system has been running for about a month now and it’s quite possibly the best thing I’ve ever built.
For your own simple aquaponics system you’ll need: 1 pond/tank/water containment device, 1 pump (pond pump or sump pump), an automatic timer for the pump, PVC piping (however much you need for your design), plants, plant containment devices with adequate drainage (the type of drainage and the placement of the drain holes is up to your design), black cinders or spongerock, plants, and fish.
Those are the most basic needs of an aquaponics system. Anything else you’ll need will be up to your design, but remember to contain the sump pump in something that allows water flow but prevents fish from getting sucked up. You must have a timer or some sort of system worked out so you don’t have your plants in water 24/7 (that causes root rot). My system turns on between 6am and 11pm for 15 minutes every 45 minutes to allow the plant boxes to drain. The system shuts off at night. If you’re concerned about the amount of water the pump pumps out of your pond then I recommend getting a PVC pipe valve that you can turn to control water flow. If you use this though make sure that your pipes are fitted securely onto the pump otherwise your pipes will just slip off due to water pressure and you’ll have a large watery mess to clean up and a few suffocatng fish.
When I post a picture of my system, hopefully it will all be a bit clearer than my words. Anyway, aquaponics systems are an awesome backyard experiment that’ll teach you and/or the kids a lot about the basic needs of fish and plants as well as a bit about how the world works. It’s easy to build and maintain, fun to watch your fish and plants grow, and it’s also rewarding when harvest time rolls around. If you plan it and time it right you’ll have fresh vegetables all year round! Just be careful when winter rolls around. Shallow systems don’t do well in cold places so if your winters are freezing, it’s best to have a deep pond so you don’t end up with fishsicles.
If you decide to launch one of these projects for yourself, good for you! I hope my extremly abbreviated lesson in aquaponics inspired you to go out and grow something.
Over and out!
-Kyanel