The fortune teller fish or magic fish is a fish-shaped strip of polymer or plastic that bends and twists when placed onto your hand. The fish is red, but there’s nothing special about its color. The polymer absorbs water from perspiration on your skin, changing it structure and warping the fish.
Whether the fish bends head-to-tail or side-to-side can be used for games, to answer yes/no questions or predict your personality. The toy is simple to make it yourself.
Homemade Fortune Teller Fish Materials
There are two different materials you can use to make a homemade fortune telling fish:
Sodium Polyacrylate Fortune Teller Fish
If you buy the toy, the fish is made from sodium polyacrylate — the same polymer used in disposable diapers and fake snow. You can collect the polymer, wet it, press it into a sheet, let it dry, and cut it into a fish shape. That seems like a lot of work! Another option is:
- Hydrate water gel beads, diaper-insides, or fake snow until they have absorbed water. Depending on the starting product, you’ll have either clear or white damp gel. If you used colored gel beads, it’s best to use beads of one color or else ones that mix together to produce an attractive hue.
- Place the gel in a blender and blend until smooth. You can add food coloring if you’d like a colored fish.
- Use a paintbrush to coat a piece of glass or metal (like a cookie sheet) with the liquefied gel. Let the polymer dry. You can apply an additional coat of gel, if you like.
- Gently peel the polymer off of the surface to get a thin sheet. This is harder than it sounds because the gel will act like a giant fortune teller fish, bending in response to the humidity of your hands.
- Use scissors to cut the gel into a fish shape. Be creative! Make shapes other than fish, too.
Cellophane Magic Fish
The magic fish was invented before sodium polyacrylate was made. The original fish was made using cellophane, which is a thin sheet of transparent cellulose. You can use cellophane to make your own fortune telling fish. The only requirement is that you use real cellophane (sometimes called cello) and not colored plastic wrap or gift wrap. Amazon sells cellophane sheets or you can find them at arts and crafts stores.
- Use scissors to cut a piece of cellophane into a fish shape (or whatever you like). A good size is about 3-inches in length.
- Cut some fish one direction and some fish the other direction on the sheet. Why? Whether you use sodium polyacrylate or cellophane, a fish will one bend one way. The direction it bends depends on the orientation of the polymer.
Do you want to compare your homemade fish to the original product? The fortune teller fish toy is available from several sellers on Amazon.
How the Fortune Teller Fish Works
Supposedly, if the fish bends its head and tail together, this indicates a friendly personality, while curling sides indicates a mean spirit. Of course, there’s no magic. It’s all a matter of science.
Sodium polyacrylate and cellulose are polymers that readily absorb water. The cross-linking of the polymer subunits forms chains. The orientation of these chains determines which direction any particular fish will bend. Another common example of cellulose is newspaper. It’s easy to tear a newspaper into strips from top to bottom. If you tear across the paper, you can see the jagged edges of the fiber. The magic fish is like newspaper, except the material is much thinner so absorbing a tiny amount of water warps the shape.
The Magic Fish and Science Education
The fortune telling fish is a great science toy because it makes kids (and adults) think! You can hand out the fish to a classroom and ask students to propose a hypothesis to explain how the fish works. While it’s water (hydration) that moves the fish, it’s common to think it might be static electricity, a temperature effect, or interaction with some other chemical in skin (oil or salt) that causes the movement. Ask students to design an experiment to determine the cause of the movement.