Fish and plants as partners
Can a fish feed a plant?
Look at this fish tank. Plants grow right above it.
Hi, I'm Finn. My waste becomes plant food.
Think of a three-way trade, where each partner gives and gets.
Fish give waste, and tiny living things turn it into plant food. Plants give back clean water.
Nobody in this trade can do it alone.
Without the fish, there is no food. Without the plants, waste builds up in the water.
Some growers raise fish and plants together. They share one loop of water.
This way of growing is called aquaponicsGrowing fish and plants together, so they share one loop of water.
See it in the glossary.
Fish live in the tank. A pump lifts water up a pipe to the grow bed.
Plants grow in the bed, and the water runs back down to the fish.
- A · fish tank
- B · pump
- C · pipe
- D · grow bed
- E · water back to the tank
Fish make waste right into their water.
If nothing takes it away, the waste builds up. Too much can make fish sick.
In the grow bed, tiny living things change the waste into plant food.
The roots take up that food. Cleaner water flows back to the fish.
Your turn. Follow the water around the loop.
Start with the fish’s dinner.
Put the loop in order.
Move the steps up or down. Then check.
- Cleaner water flows back to the fish. Right spot Not quite
- Fish eat their food. Right spot Not quite
- Roots take up the plant food. Right spot Not quite
- Tiny living things change the waste into plant food. Right spot Not quite
- Fish make waste in the water. Right spot Not quite
Put the loop in order.
The right order:
- Fish eat their food.
- Fish make waste in the water.
- Tiny living things change the waste into plant food.
- Roots take up the plant food.
- Cleaner water flows back to the fish.
Food goes into the fish, waste feeds the plants, and clean water comes back.
In hydroponicsGrowing plants in water with plant food mixed in, and no soil.
See it in the glossary, people add plant food to the water.
In aquaponics, the fish make most of it. People feed the fish instead.
Check 1 of 3
In aquaponics, where does most of the plant food come from?
Show the answer
Fish waste, changed by tiny living things. Right. Fish make the waste, and tiny living things turn it into plant food.
Check 2 of 3
What do the plants give back to the fish?
Show the answer
Cleaner water. Right. Roots take up the plant food, so cleaner water flows back.
Check 3 of 3
What moves the water up to the plants?
Show the answer
The pump. Right. The pump lifts water from the tank up the pipe.
You just learned how fish and plants help each other in one loop of water.
Next up: The bacteria you cannot see.
Go deeper: one loop of waterOpenClose
An aquaponics system keeps one body of water moving in a loop. Each day, only a small share of that water is lost.
Plants drink water and give it off from their leaves, and some dries up from the tank. So growers top up the water from time to time.
Fish food carries most of the nutrients into the system. Fish use part of it to grow, and the rest comes out as waste.
Fish food is made for fish, not plants, so the water can run short of iron, potassium, or calcium. Many growers add small amounts of these.
Aquaponics joins two ways of farming: aquaculture, raising fish and other water animals, and hydroponics, growing plants in water.
Sources
- Somerville, C., Cohen, M., Pantanella, E., Stankus, A. and Lovatelli, A. Small-scale aquaponic food production: Integrated fish and plant farming. FAO Fisheries and Aquaculture Technical Paper No. 589. Food and Agriculture Organization of the United Nations, Rome, 2014. Link
- Rakocy, J. E., Masser, M. P. and Losordo, T. M. Recirculating Aquaculture Tank Production Systems: Aquaponics, Integrating Fish and Plant Culture. SRAC Publication No. 454. Southern Regional Aquaculture Center, November 2006 revision. Link
- Deer, C., Hu, B., Dunn, B. and Dusci, J. Nitrification and Maintenance in Media Bed Aquaponics. Fact sheet HLA-6729. Oklahoma Cooperative Extension Service, Oklahoma State University, October 2021. Link
- Hargreaves, J. A. and Tucker, C. S. Managing Ammonia in Fish Ponds. SRAC Publication No. 4603. Southern Regional Aquaculture Center, December 2004. Link