Are Your Aquarium Fish Feeling Blue?

If your goldfish seem listless and aren't eating much, a call to the pet store where you bought the aquarium might not solve the problem. It turns out your fish might just be depressed.

"The neurochemical system of fish is very similar to that of humans," says Professor Julian Pittman from the College of Environmental Science at Troy University in Alabama. "We often think of fish as simple organisms, but we don't give them enough credit."

This similarity to human depression led Pittman to test new antidepressants on zebrafish in his lab. Diagnosing depression or the absence of it in fish is particularly easy, which makes drug testing much faster. How do you know if a fish is depressed? It's quite simple. Pittman places the zebrafish in a new tank and observes them. If after five minutes the fish remain in the bottom half of the aquarium, they are depressed. If they swim in the upper half, they are fine, as the normal tendency of fish is to explore any new environment. And what about the fish in your aquarium? Simply check whether they spend more time in the top half or bottom half of the tank.

How do we know the fish are depressed and not just, for example, anxious for some reason or sick? Dr. Pittman and other researchers were convinced by the way fish lose interest in everything: food, toys, exploring their surroundings. Just like clinically depressed people. Do depressed people withdraw into themselves? So do fish.

Why might your fish sink into depression? Usually, it's due to a lack of environmental stimuli, experts say. Fish are naturally curious and love new experiences, so if you toss your goldfish into a plain jar of water, don't be surprised if they become depressed within a few hours. Want to save your fish from depression? Make sure they have a large aquarium, a diverse environment, and introduce new objects or plants from time to time.

After all, even aquarium fish deserve to be happy.