5/13/2016 Does goldfish have merely three-second memory? According to a study, this is not the case at all. Goldfish has a memory span of five months. Some scientists trained a group of young fish. Each time they played a particular sound at feeding time, the fish will return. After the training, these fish were released into the sea. After five months, these fish have become adult fish and ready to serve on the table. The farmer played the sound again to the sea. Upon hearing the sound, these fish had actually come back for food. Farmer caught them. This is a new and economical method to grow fish without using cages, and fish are able to grow in a natural environment. In another test, fish were trained to nudge a lever to get food at a fixed hour each day. The evidence shows that the fish can tell the time and always come back at the correct timing to nudge the lever for food. This shows the fish is much more intelligent than we thought.