Aquaponics uses fish to provide fertilizer for plants. Similarly to hydroponics, the plants’ roots grow in liquid and are supported by non-soil media. I’ve wanted to play around with aquaponics for a while, but don’t have any room in my apartment. Solution: micro aquaponics!
This aquaponics set-up is the most basic sort: a passive system where the plants’ roots are constantly bathed in liquid rather than pumping water to the roots. It is suitable for small things like herbs. The materials are very inexpensive, although the media I used doesn’t come in small packages. Leave a comment or send me an email through my contact page if you want to try it, live in the continental US, and want to coordinate sharing some components. I went with extruded clay pellets for media because 1) they don’t float, 2) they won’t fall through the net pot into the water, and 3) they wick up moisture, unlike pebbles. I was able to get a single net pot from a local hydroponics shop, but if you need to get them online it looks like they might need to be bought as part of a pack.
- A wide mouth quart mason jar
- A 3 inch diameter net pot
- Extruded clay pebbles
- Some rock pebbles
- A betta fish
- Betta fish water conditioner (or some other way of getting rid of chlorine-containing compounds)
- Betta fish food
- A plant seedling
First, put some clean pebbles in the bottom of the jar. Next, add conditioned water. It is important to remove the chlorine compounds from the water before use, or they could kill your fish. I got a small bottle of water conditioner for about $2 at a local pet store, but you could experiment with using vitamin C to remove the chlorine from your tab water. I already do that for my air plants, but I’ve never had a betta fish and decided to baby it a bit. Let the water get to room temperature before adding your fish, otherwise you could shock it.
Add the betta fish. I let mine get used to the new container for a bit, then also gave him some time to get used to the net pot before adding any plants. The net pot will fit perfectly over the top of the jar. Make sure that the water isn’t so high that the fish can’t get to the surface. Betta fish can get some of their oxygen from the air, which is why they don’t need a bubbler to oxygenate the water. This is also important at feeding time if you use floating pellets. Flaked food isn’t recommended, because it can make the water cloudy and tends to be more wasteful.
Feed your fish twice a day. Don’t over-feed. My fish is male, and eats more than a female, and typically will eat 3 pellets per meal. Remember, betta fish are territorial and aggressive; don’t put more than one in a container. Change out about 50% of the water every 1-1.5 days while your plant(s) grow large enough to filter the water. Build-up of wastes can be toxic to the fish, but the rest of your plants will love the fish-water treat.
Next, remove the soil from the roots of a small seedling. Place a small amount of extruded clay pebbles in the bottom of the net pot. Hold the seedling in the pot, and add more pellets to support the roots and the stem. Make sure that the water level covers most of the roots. I put two mint plant seedlings in mine, plus three pieces of mint runner that had started putting down roots. The plants are still small, but they are growing quickly. They love fish water.
Be careful about where you put your jar. Betta fish like warm water, but you could fry them if you put the jar in a hot, south-facing window. Mine seems to be doing well behind some other plants in an east-facing window. It gets some direct light, but only in the morning while it is still cool.