Science Experiments: Ghost Fish

 In Science Experiments

This experiment is all about Visual Perception. These are “after images”. They happen because the light-sensitive cones and rods at the back of your eye grow tired of the colour you stare at and then when you stare at white – other colours appear! So grab your little one and experience the ghost fish for yourself!


Visual perception – after images.


  • 4 sheets of white card
  • Coloured paper – red, blue and yellow
  • Scissors
  • Black marker
  • Glue


  • Draw the same simple fish shape on each sheet of coloured paper. Cut them out.
  • Glue each coloured fish onto white card.
  • Draw a small black eye on each fish.
  • On the last white card, draw the outline of a bowl for your fish.
  • Put the cards in a bright area.
  • Stare at the eye of the red fish for 20-30 seconds, then quickly stare at the outline of the fishbowl.
  • What do you see? Ghost fish appear! (You should see a pale green/blue fish!)
  • Stare at the blue fish and a ghostly yellow fish appears!
  • Stare at the yellow fish and a ghostly blue fish appears!
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