Instead of a plant, cuttings from Pathos or Swedish Ivy can be used. Place the cut end into the hatching vessel and secure. Put a similar cutting into a glass of water. Introduce the word hydroponics . Relate this concept to fish waste.
Fish produce nitrogen waste.
This is how seaweed, algae, grasses and other plants grow in the ocean, lakes, and ponds. Explain that this makes fish waste water ideal for growing plants. The plants get the nutrients they need and help to clean the water. Describe the hatching vessel-plant set up. Have students observe the plant daily including, color, size of leaves, size of plant, and size of the root ball.