Skip to Content

Why is My Oscar Fish Laying On Its Side? (10 Causes)

Why is My Oscar Fish Laying On Its Side? (10 Causes)

This post is written to the author's best knowledge and is not intended to be used in place of veterinary advice. In addtion, this post may contain affiliate links. As an Amazon Associate I earn from qualifying purchases.

Oscar fish have proven to be among the most popular pet fish on the market. They’re also among the most loved types of cichlids.

If you’ve owned Oscars for a little bit now, you’ve likely become quite attached to them. You want to be able to enjoy your pet Oscars for as long as possible.

This is why you might get worried at first when you walk in and see an Oscar fish laying on its side. You might be concerned that this is a sign that the fish is sick or something.

Why would an Oscar fish start laying on its side? Is this negative in any way or is it nothing to worry about?

Continue reading to learn everything that you need to know about this topic. It’ll ensure that you have a full understanding of what’s likely going on.

1 – Is Your Oscar Fish New to the Tank?

If your Oscar fish is new to the tank, it might simply need more time to acclimate. You see, fish get very nervous when they’re first placed in a new tank.

Often, people don’t realize how stressful it is for fish to get transported from a pet store to a home aquarium. It’s a very strange process for the fish, and it’s going to take time for the Oscar fish to get back to normal.

At first, the fish might seem very wary of the new tank. It might not explore the environment much and you may even see it hiding more often than not.

Sometimes you might even see the fish lying at the bottom of the tank on its side. This isn’t too unusual really.

The fish needs time to get over its anxiety due to the change in the environment that it experienced. Eventually, it should get back to normal.

The water parameters in the fish tank are likely different from the fish tank at the pet store. Your parameters are likely better for the Oscar fish, but it still needs time to adjust.

This anxiety should subside as the days go by. The Oscar fish will learn to trust you. It should grow to enjoy its environment if you’re meeting all of the necessary basic care needs.

2 – Significant Stress

It shouldn’t surprise you to hear that stress can make fish lay on their sides. Stress is a huge problem in many fish tanks.

Some fish tank owners don’t realize that their fish are stressed until it’s too late. Generally, stress is going to cause fish to act differently, and it can negatively impact their health.

When fish get very stressed, they’re going to be more likely to get sick. It makes them susceptible to diseases and infections.

You certainly want to prevent stress issues in the tank. What causes Oscar fish to become stressed?

Below, you’ll get information about some of the common causes of stress. Do your best to solve stress issues to protect your fish.

3 – Overcrowded Tank

An overcrowded fish tank can easily stress an Oscar fish. Since Oscar fish are so big, they need to be kept in large fish tanks.

An Oscar fish will grow to be twelve inches long at maturity. It doesn’t like being put in a cramped environment.

Be sure to put the fish in a fish tank that is the right size. Generally, you want to keep Oscars in a 100-gallon fish tank or something larger.

Don’t try to cram too many fish in the tank either. It’s better to avoid overcrowding so you don’t have to deal with stress issues.

4 – Bullying

Bullying is something that can happen when you put Oscars in a community tank. Oscars can do well in community tank settings, but they won’t always do well if you don’t pick out the tank mates carefully.

You must pick compatible tank mates or things could go bad. If you pick aggressive fish, the Oscars might get bullied and they will wind up getting stressed.

A bullied fish might lay on its side purely out of feeling defeated. Bullying can also cause Oscars to hide a lot. Sometimes they even stop eating.

Be careful when picking tank mates for any type of fish that you choose to buy. It’s always necessary to research compatibility or you could wind up dealing with lots of trouble.

5 – Improper Nutrition

Poor nutrition will cause stress as well. As you might expect, Oscars won’t do well if they aren’t being fed properly.

Feeding the Oscars a poor diet that isn’t balanced right will lead to stress. Not feeding your Oscars enough food will also be problematic.

Do your best to feed your Oscars consistently. Stick to a schedule and make sure that the Oscars are given recommended foods.

Remember that these fish need live food to supplement their diets. You should be giving them meaty treats from time to time.

6 – Water Parameter Issues

The water parameters will play a role in the health of the fish, too. You must monitor the conditions in the fish tank to keep your Oscars healthy.

You need to keep the pH balance between 6.0 and 8.0. The best pH balance is 7.2 if you want to keep things right where they should be.

The temperature can stay between 74 degrees Fahrenheit and 81 degrees Fahrenheit. You should test the water regularly and keep an eye on both the temperature and the pH balance.

Be sure to clean the tank regularly and do weekly water changes. Failure to do this will make the water quality suffer.

Oscar fish are messy eaters that will make the water dirty faster than you’d expect. You must be proactive about tank maintenance or your fish might get stressed fast.

7 – Sickness

There are many types of sicknesses that might make Oscar fish lay on their sides. As you might know, sicknesses will have various symptoms that they are associated with.

Often, fish that get sick will wind up becoming sluggish and they will act differently. A lethargic fish might lay on its side at the bottom of the tank when it’s not feeling well.

There are all sorts of illnesses that you should know about. Oscar fish commonly have to deal with issues such as hole in the head disease, popeye, fin rot, tail rot, and ich.

All of these conditions might cause the fish to lay on its side. Thus, if you see the fish laying down like this, it’s a good idea to try to determine if it’s sick.

Look out for other common symptoms that will help you to pinpoint what is wrong. For example, a fish that has white spots all over its body very likely has ich.

If you need help identifying the type of sickness that your fish has, you can reach out to an exotic veterinarian. This will cost money, but it can make it a lot simpler to determine what’s wrong and start treating the fish.

Thankfully, there are many types of treatments that you can turn to. If your fish has ich, there will be medications that you can buy at pet stores to clear the issue up.

8 – Swim Bladder Problems

Have you considered whether swim bladder issues could be to blame? If you don’t know, the swim bladder is an organ that controls buoyancy.

Many fish have swim bladders and they can’t swim normally when the swim bladder isn’t working. Sometimes swim bladders will malfunction due to being compressed.

A swim bladder is actually just a gas-filled sac that inflates and deflates as necessary. Sometimes certain things will press against the swim bladder and this will prevent it from functioning normally.

For example, a fish might become bloated and the swollen belly of the fish will press against the swim bladder. This prevents the sac from being able to inflate with air.

Injuries and infections can also cause swim bladder malfunctions. When the swim bladder is having issues, fish have a tough time swimming around.

They might swim in circles or they may even swim upside down. In some cases, fish don’t move much at all and simply lay at the bottom of the tank on their sides.

To fix this issue, you’ll have to determine what is wrong. Constipation can be fixed by feeding the fish boiled peas to its digestive tract moving again.

An infection can cause intestinal swelling that will cause the swim bladder to malfunction. This can be cleared up with antibiotics.

Physical injuries may simply have to heal on their own. In some cases, a swim bladder might become permanently disfigured due to a particularly bad injury, and the problem won’t ever get better if that’s the case.

9 – Submissiveness

It’s said that Oscar fish will sometimes lay on their sides as a sign of submission. This can happen when one male Oscar fish has defeated the other in a show of strength.

Oscars will fight for various reasons in the wild and in captivity. If you’re keeping two male Oscars in the same tank, they might fight over territory or potential mates.

When one Oscar fish wins the squabble, you might see that the defeated fish will lay on its side. This is a sign that it has been defeated and it acknowledges that it must now take on a submissive role.

Fish fight to determine the “pecking order” in the fish tank. As the fish age and grow, the pecking order will change.

There’s a good chance that you’ll notice things like this happening when you’re caring for a small group of Oscars. A fish laying on its side is simply a sign that the fish has given up the fight.

Some fish tank owners don’t like the idea of the fish fighting. You might wish to avoid keeping multiple male Oscars in the same tank if you want things to be peaceful.

It’d likely be easier to keep one male and one female Oscar in the same tank. It’s also perfectly acceptable to keep one Oscar fish by itself since these fish do fine in solitude.

10 – It Could Be Normal

There’s anecdotal evidence that suggests that some Oscars lay on their sides normally. This might simply be typical behavior for certain types of Oscar fish.

If you are sure that nothing is wrong in the tank and your fish isn’t sick, there might not be anything to worry about. Of course, it’s best to check everything first so you can be sure that everything is okay.

Many Oscar fish enthusiasts say that a fish laying on its side isn’t always a sign that something is wrong. It could be that the fish just does that when it’s resting sometimes.

Some people chalk it up to a behavioral quirk. So try not to worry too much if everything in the tank seems fine and you can’t figure out why the fish is laying on its side.

You can continue to monitor the fish to be on the safe side. If the fish is eating normally, appears to be healthy, and the water parameters are good, it’s likely nothing to be too concerned about.

Final Thoughts

Knowing more about what causes Oscars to lay on their sides will help you out. Now you have an understanding of the situations that can lead to this happening.

In some cases, it’s going to be important to pay attention to what’s going on. Otherwise, your fish could be sick and you won’t be able to help in time due to it being too late.

Sickness can indeed cause fish to lay on their sides. Your fish could have a disease or it might be dealing with some type of infection.

General stress can cause fish to act this way as well. Often, fish will start acting sluggish and laying on their sides when they’re overly stressed.

Try to resolve stress issues in the tank to get the fish feeling better. You might need to change multiple things to truly solve the problem.

Of course, it could be that nothing is wrong at all. Perhaps laying on its side is normal behavior for the Oscar fish.

Some Oscar fish owners say that a fish laying on its side is simply a behavioral quirk. It’s still likely wise to pay attention to what’s happening to be safe, but it’s possible that nothing is wrong at all.