Sounds Fishy: Do Goldfish Have Water Temperature Preferences?

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Updated on Aug 29, 2011

Find the relative temperature (warmer or cooler) that pet goldfish prefer.

Pet goldfish can withstand a rather wide range of temperatures. Are they more comfortable in water that is above or below room temperature? Finding out which temperature they prefer, and then giving them that temperature, may make for healthier, longer-living pets.

Hypothesize that water temperatures above room temperature (within reason) are more desirable to goldfish than water temperatures below room temperature, as evidenced by their spending more time in the area of an aquarium they prefer. (Or, you may choose to hypothesize the opposite.)

  • Piece of Plexiglas
  • Nontoxic bonding glue for plastic and glass
  • Aquarium
  • Several goldfish
  • Two thermometers
  • Fish tank heater
  • Several ice cubes

Position a board or a piece of Plexiglas in an aquarium tank. It should extend from the top to the bottom of the aquarium, and when placed in the center of the tank, a 1-inch gap should be around one of the sides to allow the fish to freely swim from one side of the tank to the other. Secure with glue and let dry.

Get two thermometers. Lay them side-by-side on a table and allow them to sit for about 15 minutes to stabilize at room temperature. Both thermometers should read the same temperature. If one reads differently, mark it with a marker and note the difference in temperature. You will need to account for this difference when you make temperature readings in the water.

Fill the aquarium with water. Let the water stand for several hours until it reaches room temperature.

Place a fish-tank heater in one side of the aquarium. Place several ice cubes in the other side. Position two thermometers in the tank, one in each side.

Introduce the goldfish into the water and observe them for several hours. Do the fish spend more time in one section than the other? What is the temperature difference between the two sides?

Write down the results of your experiment. Document all observations and data collected.

Come to a conclusion as to whether or not your hypothesis was correct.