Choosing fish and plants that get along
Can any fish live with any plant?
In aquaponics, fish and plants share one loop of water. So they have to like the same things.
Not every fish likes the same water. Let's find good matches.
Picture two roommates who share one thermostat. One likes it warm, and one likes it cool.
Whatever they set it to, somebody is never comfy.
Fish are like that too. Some like warm water, and some like cool water.
Tilapia like it warm, and trout like it cool.
The plants’ roots sit in that same water.
So growers pick fish and plants that like the same temperature. Then everyone in the loop is comfy.
Leafy greens and herbs grow fast and need little plant food.
That makes them a good fit for a new or small system.
- A · lettuce
- B · basil
- C · kale
- D · tomato
- E · pepper
Plants that make fruit, like tomatoes and peppers, need more food.
They do best in an older system with plenty of fish.
- A · lettuce
- B · basil
- C · kale
- D · tomato
- E · pepper
Your turn: which plants fit a new system?
Sort each plant into the place where it grows best.
Where does each plant fit best?
Tap a card, then a bin. Or press 1 or 2 on a card.
- Nothing here yet
- Nothing here yet
Where does each plant fit best?
The answer:
Good for a new, small system
- Lettuce Lettuce is a leafy green. It grows fast on a little food.
- Basil Basil is an herb. Herbs need little food.
- Mint Mint is an herb. It grows well on a little food.
- Chard Chard is a leafy green, like lettuce.
Better in a big, older system
- Tomatoes Tomatoes make fruit, and fruit needs lots of food.
- Peppers Peppers make fruit, so they need a well-fed system.
- Cucumbers Cucumbers make fruit, and fruit needs lots of food.
A fish or plant let loose outside can spread and harm local wildlife. A living thing that does that is called invasiveA living thing from somewhere else that spreads in a new place and causes harm there.
See it in the glossary.
So never release fish or plants outdoors, not into ponds, streams, or drains.
Some fish are not allowed in some places. So growers check the local rules before they pick their fish.
If a fish can’t stay, an adult finds it a new home.
Check 1 of 3
Why should the fish and plants in one system like the same temperature?
Show the answer
They share the same water. Right. One loop of water flows past the fish and the roots.
Check 2 of 3
Which plant is a good pick for a new, small system?
Show the answer
Lettuce. Right. Leafy greens grow fast and need little plant food.
Check 3 of 3
A class can't keep its fish anymore. What should it do?
Show the answer
Ask an adult to find the fish a new home. Right. A new home keeps the fish safe, and it keeps wild places safe too.
You just learned how to match fish and plants, and why they never get let loose outside.
Go deeper: temperatures and hungry fruitOpenClose
Books differ on the exact numbers, so treat these as rough ranges. Tilapia grow best in warm water, about 27 to 30 °C (81 to 86 °F).
Below about 17 to 20 °C (63 to 68 °F), tilapia grow poorly. Guides differ on the exact point.
Rainbow trout need cool water. They grow best at about 10 to 16 °C (50 to 61 °F), and guides differ here too.
Plants have favorite temperatures too. Lettuce is a cool-season crop, while tomatoes and peppers like warm weather.
Fruiting plants need more food than leafy greens. Tomatoes short of calcium can get a dark, leathery spot on the bottom of the fruit, called blossom-end rot.
Fish food often has too little potassium, calcium, and iron for plants. That is why many growers add small amounts of them.
Many governments limit which fish may be brought in, moved, or released, because some could harm wildlife. The rules differ from place to place.
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
- Mullins, C., Nerrie, B., and Sink, T. D. Principles of Small-Scale Aquaponics. SRAC Publication No. 5007. Southern Regional Aquaculture Center, September 2015. 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; Oklahoma Cooperative Extension Service. Link
- Sallenave, R. (revised by). Growing Trout in New Mexico Ponds. Guide L-108. New Mexico State University Cooperative Extension Service. Link
- Cool Season Vegetables. Cornell Cooperative Extension of Monroe County. Link
- MacSwan, I. C. Blossom-end Rot of Tomatoes. FS 139. Oregon State University Extension Service, revised March 2024. Link
- National Invasive Species Information Center, U.S. Department of Agriculture. What are Invasive Species? Link
- U.S. Fish and Wildlife Service, La Crosse Fish Health Center. Fish Surrender Program. Link
- Fisheries and Oceans Canada. Don't let it loose. Link
- U.S. Fish and Wildlife Service. Understanding Injurious Wildlife Regulations. Link