In this activity, learners cut out a fish and then "paint" it using universal indicator and acids and bases. The initial coat of indicator changes the color of the paper (it will turn a salmon color if the paper is acidic, and green if it is considered acid-free). From there, adding acids (such as lemon juice) and bases (such as laundry detergent) will further change the color. Universal indicator responds to a wide range of acids and bases, so other home chemicals (shampoo, vinegar, etc.) could be tried to create different colors. For older learners, a paper pattern other than a "rainbow trout" (such as a rainforest bird or other colorful animal) can be used.