Lesson guide · Lesson 20 · Grades 3–8 · 6 min

Choosing fish and plants that get along

How to pick fish and plants that like the same water, which plants suit a new system, and why fish and plants never go outdoors.

Open the lessonPrintable worksheet

Students will

  • Explain why fish and plants in one system need to like the same water temperature.
  • Name plants that suit a new, small system and plants that suit a bigger, older one.
  • Explain what invasive means and why fish and plants are never released outdoors.

New words

invasive
A living thing from somewhere else that spreads in a new place and causes harm there.

Talk about it

Have you ever shared a room, a car, or a classroom with someone who liked it warmer or cooler than you? How did you work it out?

Check questions and answers

  1. Why should the fish and plants in one system like the same temperature?

    • They share the same water (answer) Right. One loop of water flows past the fish and the roots.
    • The plants keep the water warm Not quite. Plants don't heat the water. They share it with the fish.
    • The fish eat the plants Not quite. In aquaponics the fish don't eat the plants. They share the water.

  2. Which plant is a good pick for a new, small system?

    • Lettuce (answer) Right. Leafy greens grow fast and need little plant food.
    • Tomatoes Not quite. Tomatoes need lots of plant food. They suit older systems with plenty of fish.
    • Peppers Not quite. Peppers make fruit, so they need more food than a new system has.

  3. A class can't keep its fish anymore. What should it do?

    • Ask an adult to find the fish a new home (answer) Right. A new home keeps the fish safe, and it keeps wild places safe too.
    • Let the fish go in a pond Not quite. A released fish can spread and harm the wildlife there. Never release fish outside.
    • Pour the fish down a drain Not quite. Never put fish down a drain. Ask an adult to find them a new home.

Teacher note

Follow your school's animal policy if your class keeps fish; an adult is in charge of their care. Rules on which fish may be kept, moved, or sold differ by place, so check with your local wildlife or fisheries agency. Classroom fish and plants are never released outdoors or into drains; if a class can't keep them, an adult finds them a new home.

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.
  • Mullins, C., Nerrie, B., and Sink, T. D. Principles of Small-Scale Aquaponics. SRAC Publication No. 5007. Southern Regional Aquaculture Center, September 2015.
  • 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.
  • Sallenave, R. (revised by). Growing Trout in New Mexico Ponds. Guide L-108. New Mexico State University Cooperative Extension Service.
  • Cool Season Vegetables. Cornell Cooperative Extension of Monroe County.
  • MacSwan, I. C. Blossom-end Rot of Tomatoes. FS 139. Oregon State University Extension Service, revised March 2024.
  • National Invasive Species Information Center, U.S. Department of Agriculture. What are Invasive Species?
  • U.S. Fish and Wildlife Service, La Crosse Fish Health Center. Fish Surrender Program.
  • Fisheries and Oceans Canada. Don't let it loose.
  • U.S. Fish and Wildlife Service. Understanding Injurious Wildlife Regulations.