This is why Tapping on the Glass is not good (2022)

This is Why You Can’t Tap On a Fish Tank

If fish appear sluggish in an aquarium, one of the first things many new tank owners do is tapping on the glass. While it can be enough to make fish liven up a little, it doesn’t mean this is doing them any good.

Even in stores, you see tanks that say do not tap on the glass, so is it a big issue with tapping on your aquarium?

This is why you can’t tap on a fish tank. Once you tap on a tank, the sound waves increase, and the noise becomes amplified. One of the main things that happen when anyone taps are that fish begin stressing out. Where they look as they are livening up and coming out to play, they are, in fact, being startled and stressing as if something was chasing them.

What Happens by Tapping on the Glass of an Aquarium?

Sound travels in waves, and it doesn’t matter if this is through the air or underwater. For humans, it is through the air, and we hear the sound as our eardrums begin vibrating. These then translate into meaningful sounds as the brain interprets them.

The closer we get to the source of noise, the louder it becomes, and with this, the louder something becomes it can lead to pain, if we don’t use any ear protection.

If sound acts the same way underwater, then it may not be so much of an issue. However, sound travels much faster, and up to five times faster, and the waves amplify as the entire body of the fish can feel them in comparison to human ears.

Finally, the sound will travel greater distances underwater; thus, this is why a fish will come out of hiding if you are tapping on the glass. They are unable to sense the direction of the sound, and it triggers their survival mode.

How Do Fish Stress With Sound?

Although there are no apparent signs of ears on fish, we can determine they can hear and are sensitive to sudden and loud noises. In addition, it triggers their flight or fight responses. In the cases of fish, they are often going to opt for the flight decision and try to escape.

Once you start tapping on the glass, and see fish darting. They swim at these speeds when under threat. At that moment, they will be full of adrenaline and are not aware of where they are swimming. It is possible for them to hit rocks or even plow straight into the glass of the aquarium. It can even be enough for some fish to leap from the top of the tank if there is no lid.

How Do Fish Stress With Sound

The issue with these adrenaline spikes is they quickly exhaust fish inside aquariums because of increased heart and breathing rate, as well as an increase in blood pressure.

Fish in the wild can cope with this, as they can escape to somewhere quieter. Yet, inside a tank, they quickly suffer, and with the induced stress, their cortisol levels increase.

Cortisol is the stress hormone, and while we can become agitated, fish can suffer from stunted growth and start to have digestive issues. Once they reach this stage, another raft of problems will follow. The immune system of fish weakens when they stress, and they become vulnerable to parasites and disease.

How Do Fish Listen?

Fish don’t have ears, visible or not, yet they do have their own means of hearing. By using otoliths and lateral lines, fish can hear and feel vibrations in the water. Not only does it aid their hearing, but it also allows them to sense how strong water currents are.

How Do Fish Listen

Aside from hearing, they act much in the same way as human ears and help fish balance. The hearing mechanisms in fish serve many purposes, and more in tune toward survival rather than just hearing, as we perceive what hearing is.

Grabbing Attention without Tapping on the Glass

Depending on the types of fish you have, you may find some are shyer than others are. It may be natural to tap to coax them out of hiding, yet you can see from the above, this can be more harmful than helpful.

It can help to try to determine why your fish are hiding away so much in the first place. One of the primary reasons is you have one kind of fish, which has a more aggressive nature, and your other fish are giving them their space, and keeping out of their way.

If this is the case, it could be advisable to separate the more aggressive into another tank, and thus let your other fish swim around in a more natural fashion.

One other thing new tank owners often overlook is the type of fish they have and their habits. Are your fish nocturnal and sleeping during the day? It can be a shame to set up an aquarium to find all your fish are asleep while you are awake, and it is worse trying to coax them out of their bed so you can see them.

It is possible to purchase aquarium lights that act in a specific manner and can induce night light so fish will come out earlier.

If your fish are regular daytime fish, then one way to coax them out can be food. It is possible to create a bond with your fish, and once you begin feeding them, they may prevent skulking away in the shadows and come out to play more often.

Grabbing Attention without Tapping on the Glass

Feeding them their usual flakes may not do the trick, yet if you select some treats like brine shrimp, bloodworms, or daphnia, then they may appreciate the gesture more. You can find these tasty fish treats online or at your local pet store.


We have seen that fish can hear in different ways to us, and the way sound travels underwater, what sounds like a gentle tapping on the glass to us, can sound like a giant bell going off inside an aquarium. The listening organs in fish are very acute because they are intended for defense mechanisms, and for sensing the conditions of their surrounding habitat.

For the same reason, as not to start tapping on the glass, your aquarium should sit away from any areas where there are constant loud noises, such as music or TV’s. Even a home that has young children who rap their small knuckles on the tank glass can be sufficient to harm your fish.

If this is the case, then a little education can help kids understand the effects they are having on the fish, and how they may harm them.

Fish like the peace and quiet, and when they have the ideal conditions, they will come from their hiding places and begin swimming around once they realize they are not under any threat.

Making sure your fish are living in a peaceful environment, will mean they can live longer and will be healthier as a result without continual stress from you tapping on the glass of the side of your tank.