Can tapping on glass kill fish?

Tapping on glass does not kill fish however repetitive tapping can cause enough distress to shorten the lifespan of your fish.

Yes, a single tap is not fatal but does that mean it is okay to tap once in a while?

You must have observed that every time you tap on the glass, fish displays behavioral change. If they are feeding, they will swim away from feeding site. If they are resting, they will immediately swim in a frantic way. You will notice increased swimming activity. Why is that?

People often tap on the glass to make fish emerge out of it’s hiding place or to draw their attention without fully understanding the detrimental effect it has on fish health.

So, let’s look into why you should refrain from tapping on aquarium glass.

Causes Stress

For your fish well being, it needs to feel safe in it’s environment. Any tapping sound you make on aquarium glass scares your fish. When your fish is scared, it is in fight or flight state. If it experiences tapping sound frequently, it presumes aquarium to be an unsafe environment. This is very stressful for fish. Stress increases heart rate, respiration and elevation in blood pressure. It also triggers the release of stress induced hormones including adrenaline and cortisol.

Adrenaline boosts energy supplies needed for extra energy demand due to stress. This assist in quick and sudden action required to face the changes in environment.

Cortisol curbs physiological function that can get in the way of fight or flight response. This means your fish will be mobilizing energy to face the danger and not for non-essential activities like digesting food. So, short term rise in cortisol level is helpful and even necessary but if there is prolonged elevation of stress hormones in fish, it is going to have devastating effect on fish health. These include lower immune system, weak digestive system, reproduction problems and it can also stunt the growth of fish.

In wild, fish response to stress is to flee but in a confined environment like fish tank, your fish can feel that it cannot escape the threat. This exacerbates the problem.

Causes temporary hearing loss

Before you tap on aquarium, consider this fact. Sound appears louder underwater than in air because sound travels faster in water than in air. If you make repetitive tapping sound, it can seriously diminish the hearing abilities of your fish. Fish like goldfish and rosy red minnow are more susceptible to hearing loss due to their hearing sensitivity. Research has shown that they are able to regain their normal hearing level however they remain stressed until fully healed. They can feel vulnerable because they use sound to communicate with other tank mates and learn about their surrounding.

Their recovery period will depend on the intensity and duration of their exposure to the tapping sound.

Increases the possibility of bodily harm

You should not cause any disturbance to your fish tank and tapping sound does exactly that. It induces alarm response in fish. It perceives sudden unexpected underwater noise to be a threat. Your fish automatic reaction is to swim away as fast as possible from tapping sound or towards tapping sound. This alarm response behavior can easily injure your fish because while fleeing they could swim into aquarium decoration or bump into other fish causing bodily harm to itself and other fish. They could also hit the side of aquarium glass which can momentarily stun them.