In aquarium fish, a long-term memory for the voices of people living nearby was revealed. In the study, scientists from Ohio State University introduced 50 aquarium fish to the voices of different people, developing a conditioned reflex: a connection between one of the voices and a treat.
The selected fish were attracted by special food – near the dynamics of the animals, food was waiting. Over time, the sound was mixed with a certain voice and gradually replaced by it, but the reward remained the same. Periodically, instead of one voice, others were turned on, but aquarium fish learned to pick up differences, and eventually they stopped swimming at sounds that did not promise a reward.
The animals were then microchipped and released into the wild. A few years later, some of them were caught, and the experiment was repeated. All individuals, as in previous years, responded to the correct voice and swam for the reward, while untrained fish only moved their fins from the sounds.
Now scientists suggest to repeat similar experiments with river and sea fish, and find out exactly what moments of life they remember for a long time.