A lot of people have the belief that fish are not intelligent and often fish characters can be portrayed to be forgetful (Dory in Finding Nemo). However, it turns out that is not what has been found in studies. It was found that fish may actually be able to remember things for up to 3-5 months. According to research at Plymouth University "goldfish have a memory span of up to three months - and can even tell the time." This demonstrates the falsifiability principle of scientific thinking. It turns out that fish can even be classically conditioned "Researchers from the Technion Institute of Technology in Israel trained young fish to associate a sound played through a loudspeaker with feeding time. Each time they played a particular sound, the fish would return for food." Those same fish were later released into the wild to develop after a month of training and about 5 months later, the scientists played the sound again and the fish returned. Another example of fish being classically conditioned was training goldfish to press a lever to get food, but the lever would only dispense food during one hour each day. It was found that the goldfish would adapt and learn when to press the lever each day. Furthermore, a whole group would cluster around the lever as feeding time drew closer.
There were some interesting facts and practical applications found with the study of the memories of fish. It was found by scientists at St. Andrews University in Scotland that minnows are at least as intelligent as rats (that can also be said of sticklebacks and guppies). Also, other studies have shown that goldfish have the ability to learn and remember and that "they outshine trout in intelligence stakes." Lastly, it was found "they can learn their way around mazes, they can learn to recognize other fish, and they can remember which individuals are better competitors." A good application of this find is that the cost of cages, staff, and feeding of the fish would all be cut, along with the impact on the environment. Perhaps this will teach us to not be so quick to underestimate the intelligence of a fellow creature next time.