Goldfish adaptations include the ability to see several different spectrum of light, heightened hearing and eyesight, polarized and motion sensitive eyes, and a lateral line. Goldfish have additional cone cells in their eyes that allow them to see into the red, green, blue and ultraviolet spectrum.
The combination of the fish's polarized and motion sensitive eyes help it to see objects, like clear-bodied brine shrimp, that would be almost invisible to the human eye. Goldfish also have heightened eyesight that allows them to see objects that are up to 14 feet away. In general, fish are able to sense long distance sound waves because they have a swim bladder that is close to their ear. The swim bladder acts as an amplifier. In goldfish, sounds are amplified even more due to a bone that connects the swim bladder to the goldfish's inner ear. This allows goldfish to hear frequencies up to 2,000 hertz, which helps with hunting as well as escaping predators. The lateral line on goldfish also helps detect disturbances and vibrations in their environment. The lateral line is a water filled canal that runs the length of the goldfish's body. Tiny holes in the goldfish's skin allow the outside water to fill the canal. Tiny hairs extend from the goldfish's body into the water inside the canal and are used to detect vibrations in the water surrounding the fish.