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Why is My Fish?…Unique Fish Tank Behaviors

Fish Behaviors

We do not spend time with our fish like we do with our cats or dogs. However, it is just as important that we understand their behavior and get to know what is and isn’t normal for them. 

It is critical to remember that every fish will not have the same ‘normal’ behavior. Just like any animal, fish are individuals, and not only that, but every breed of fish will have a different normal behavior; a guppy will not have the same behaviors as a betta fish for example.

Make sure that whatever fish you have, that you understand and know what their normal behaviors are, understand the typical behaviors of the fish you have before you buy them, and then watch them on a regular basis, so you will know if something is awry. If your fish behavior is concerning you, check out to find out more. 

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Behavioral Changes

If you know your fish well, and they suddenly start acting differently, you will be concerned, it is only natural to be concerned in this situation. However, behavioral changes are not always a cause for concern. Their behavior can change due to breeding, or a minor issue inside the tank, it is not always serious. 

But, being vigilant and understanding what behavior is normal and what behavior is concerning in your fish is the key ingredient to catching out any issues early on. 

Normal or Concerning

There are some unique fish behaviors that may be confusing, and when we are faced with confusing behaviors, we often get worried straight away. But, sometimes these behaviors are actually normal. 

Since we do not spend as much time with our fish as we do with other pets, we might not notice all of their normal behaviors all the time. Always check and research the behavior you see before you run around panicking that something is wrong. 

So, we’ve taken some common unique fish behaviors, and now we will answer the question for you; normal, or concerning? 

Laying at the bottom of the tank

If your fish is spending a lot of time at the bottom of the tank, it can be totally normal. This is a reason to know your fish, as some are bottom feeders and just like it down there. Fish also typically sleep at the bottom of the tank as well. 

If you have a fish such as a betta, this behavior is sometimes normal, and there are many possible reasons for a betta fish to be hanging around at the bottom of the tank. This could be anything from aging, water being too hot, having a lazy day, an aquarium that is too small, sleeping, to being something more drastic such as ammonia or nitrate poisoning, or disease such as swim bladder disease.

If the fish is definitely not sleeping, the aquarium is not too small, and the behavior is continuous, then you might want to be concerned as it could be something like swim bladder disease. So, if you find your betta fish laying on the bottom of the tank, it might be a cause for concern.

Loss of appetite

It is not actually all that uncommon for aquarium fish to lose their appetite every now and again, much like us, sometimes they just aren’t feeling it. However, if it is a change that begins to affect their health and wellbeing,  you might need to step in. A long-term loss of appetite is usually a symptom of disease in aquarium fish, so if you notice this, spend a few minutes observing their behavior for other symptoms to help you pinpoint the illness that might be causing them issues. 

DO note that sometimes a fish will just lose their appetite because they are bored with their diet, and some species are very picky eaters and might refuse to eat if not getting the variation in their diet that they want. This is especially common in saltwater aquarium fish. 


If you find your fish hiding, it is normal. It is actually a very natural behavior for most fish, especially if they have just been introduced to a new aquarium. All you need to do is make sure they feel comfortable and healthy, and eventually they will start to come out of hiding a little more.

Erratic swimming

Erratic swimming could be play and exercise, however, if they do this all the time, and they seem to be less healthy it can be due to poor water quality. Test your water’s pH for ammonia and nitrates immediately to see if anything is awry. 

If everything else is fine it could be a parasite, it could also be an external parasite if they rub themselves against something in the tank and then swim away quickly.

Quick swimming can also be a sign of breeding as well, depending on the variation of fish you have, it is not impossible that this behavior can be related to breeding behaviors. 

Gasping for air

Should your fish look like they are gasping for air at the top of their aquarium, then there is an issue with the water. It can be a sign that there is not enough dissolved oxygen in the water. Test the water quality and consider getting an aerator for the tank. 


If your fish are fighting, then it basically means they shouldn’t be housed together. Many fish can be naturally aggressive and will defend their territory til the death. Before you stock your aquarium full of fish, do research on which fish are compatible with each other. 

You should try to keep a variation between top and bottom feeders, and ensure your aquarium is large enough to accommodate all fish. Provide plenty of hiding places inside the tank and change the scenery from time to time, especially if you are adding in new fish, as to eliminate any territorial disputes. Also try to keep a good variety of different fish types as well. 

Doing all of the above should eliminate violence, but of course this is something you need to think about prior to getting your fish.