First domesticated during the Chinese Sun Dynasty more than 1,000 years ago, thanks to selective breeding, there are now more than a 100 types of goldfish. Though some people claim goldfish aren’t the brightest bulbs in the tank, researchers are making discoveries that may blow this theory out of the water.

A study conducted by Jonathan Lovell at Plymouth University found that some fish can be successfully trained to swim toward a particular sound. To test his theory, Lovell plans to release domesticated “trained” fish into the sea and call them to a special feeding station by playing a sound the fish have learned to associate with food.

At the University of Edinburgh, Cullum Brown studied two groups of fish: those who knew their tank well and those who had just been introduced to the tank.

Brown placed a net with a central hole into the tank, sweeping it from side to side. Fish that were familiar with the tank were able to more easily escape through the hole in the net.

Brown hypothesizes that the “familiar fish” understood their tank and didn’t view it as a threat. This allowed them to focus on the newly introduced threat — the net — and more easily and quickly find a way to escape it.

Amazingly, when Brown conducted the same experiment with the fish 11 months later, the familiar fish remembered the net so well that they were able to easily escape again.

While 11 months may not seem like a long period of time, it is nearly one-third the life span of Brown’s fish participants. That would be like a human remembering how to perform a task they had completed only once — 25 years later!

Many owners claim their goldfish have learned to recognize their faces and will swim to the edge of the tank when they see them approaching. Some even claim their goldfish have learned how to “beg” for food and will hover at the surface of the tank when people walk into the room.

If this is true, the goldfish have mastered “associative learning” by recognizing that when humans show up, sometimes food does too. This is the same principle Ivan Pavlov explored in his famous experiment when he trained dogs to associate the sound of a ringing bell with the arrival of food.