Skip to Content

Why Is My Oscar Fish Not Active? (4 Common Reasons)

Why Is My Oscar Fish Not Active? (4 Common Reasons)

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.

It’s no secret that Oscar fish are some of the best pet fish you can buy. These fish are so much fun to care for.

If you own an Oscar fish, you already know how great they are. They’re large fish that can be a bit tough to find room for, but they’re great for those that live in homes that can fit bigger aquariums.

Caring for Oscars won’t be too hard either since they’re hardy fish. Even if they are hardy fish, they can still experience problems sometimes.

Has your Oscar fish been less active than usual as of late? Perhaps the Oscar appears to be somewhat sluggish and it’s beginning to worry you.

What does it mean when an Oscar fish stops being active? Is this a sign that the fish is getting sick?

Continue reading to learn about Oscars and what a lack of activity indicates. This should allow you to take the right actions to protect your fish.

1 – The Oscar Could Be Injured

Oscar Fish With Several Sores on Its Chin

One possibility that you must consider is that the Oscar might be injured. The Oscar fish could have been hurt somehow while living in the tank.

This can happen for a number of different reasons. The Oscar fish might have become injured due to fighting with another fish.

Another possibility is that the Oscar rammed into an object in the tank and hurt itself. This can sometimes happen with fish in an aquarium setting.

Have you handled the fish recently? Sometimes fish owners will accidentally harm their fish when transferring them to a new tank.

Try to examine the fish and see if it appears to be injured in some way. If you need advice, you could ask an exotic veterinarian for assistance.

A professional can more easily determine if a fish is injured. They will also be able to give you appropriate advice that will help you to treat the fish if necessary.

2 – Could the Fish Be Sick?

It’s quite possible that the Oscar fish is sick. Fish will get sick after they’ve become stressed.

Stress compromises the immune system of the fish and makes them more susceptible to sickness. Your fish could have an illness and this is making it lethargic.

If you see that your fish isn’t swimming much at all, it’s likely that it’s sick in some way. You can observe the fish and take note of its symptoms.

There are many diseases that Oscars might have to deal with. Sometimes it might be difficult to determine exactly what is wrong at first.

Often, it’s going to be easier to reach out for professional help. An exotic veterinarian can diagnose the fish and tell you exactly what is wrong.

If you don’t want to spend the money to get such help, it’ll be best to monitor the fish and try to diagnose the issue on your own. Once you figure out what type of sickness the fish is dealing with, you can look into appropriate treatment options.

Since Oscars are hardy fish, they have the potential to survive many types of sicknesses. Often, the survival of the fish will depend on how quick you catch the problem as well as how proactive you are about treating the issue.

3 – Cramped Conditions in the Tank

Too Many Oscar Fish in a Fish Tank

Since Oscars are rather large fish, it makes sense that they won’t like being put in cramped environments. These fish won’t do well if you put them in fish tanks that are too small.

You must take the time to buy an aquarium that will suit these fish. Ideally, you want to keep them in a 75-gallon fish tank or a 100-gallon fish tank.

Most enthusiasts agree that keeping two Oscars in a 100-gallon aquarium is the best choice. Not everyone will have enough room for such a big fish tank, but it’s going to be the best bet when you want to keep these fish happy.

It’s also possible to overcrowd the fish tank by putting too many fish in there. You can keep Oscars in community tanks, but they won’t be happy if you make them live in an overcrowded tank.

Be mindful of how much space each fish needs to thrive. It’d be better to get a separate tank for certain fish instead of stressing your Oscars by adding too many fish to the aquarium.

4 – Incompatible Tank Mates

You should also know that Oscars are somewhat aggressive fish. They aren’t the best community tank fish, but they can live in community tanks if you make good choices.

Pick compatible tank mates so everything will go well. You need to research the right fish so that the Oscars will thrive.

Silver dollar fish will work as tank mates for Oscars and so will many types of catfish. Pick the wrong tank mates, and things will go very bad.

Incompatible tank mates might cause the Oscars significant stress. The Oscars might be sluggish due to certain tank mates being too aggressive and bothering them all the time.

You want to fix issues like this as soon as you can. In some cases, putting incompatible tank mates in an aquarium with Oscars could lead to the fish dying.

The Oscars might kill the other fish or it could be that the other fish will kill the Oscars. You don’t want that, and that’s why you need to do the necessary research before putting a community fish tank together.

Oscar Fish Sulking

Oscar Fish Resting at the Bottom of the Aquarium

What does it mean when you see Oscar fish sulking in your tank? Surely this isn’t a good sign.

It’s an indication that the Oscar fish isn’t happy with something in the tank. Generally, when Oscars start sulking it’s a sign that something has changed in the tank.

It could be that the water parameters are slightly off. The temperature of the water might have changed or the pH balance might need to be adjusted.

Other changes can cause Oscars to sulk as well. For example, they might start sulking if they aren’t being fed properly.

Sulking isn’t something that the fish will do for long periods of time. Even so, you should take the sulking as a sign that you need to make changes in the tank to keep the fish happy.

You don’t want the Oscars to become stressed. Stress issues will make it more likely that the fish will get sick.

Do Oscar Fish Sleep?

Oscar fish actually do sleep for a certain amount of time each day. They’re diurnal fish and that means that they sleep during the night and they’re more active during the day.

On average, Oscars are going to sleep between eight and twelve hours during the night. Once the sun goes down, Oscars are going to get ready to go to sleep.

They need to rest during the night so they can remain healthy. If they aren’t able to rest properly, it’ll cause issues.

Oscars need a normal day and night cycle to be able to sleep normally. This means that they require a period of sunlight and they need things to be dark enough at night so they can sleep.

When Oscars are sleep deprived, they wind up being irritable and will sometimes be sluggish. In many ways, they react the same as humans who are sleep deprived.

Do Oscar Fish Yawn?

Two Oscar Fish With Mouths Wide Open

Have you seen your Oscars yawning in the fish tank? You might be wondering if these fish are capable of yawning in the same way that humans are.

Oscars do indeed make a motion with their mouths that seems similar to a yawn. However, what the fish is doing isn’t likely a yawn at all.

Sometimes this mouth motion could be related to problems with the water parameters. If the nitrate levels are too high in the tank, the fish might be having a tough time breathing.

This means that you’ll need to check the water parameters and make things right to protect the fish. Many fish enthusiasts note that their fish do this “yawning” motion when the parameters are perfect, though.

Anecdotal evidence suggests that this is just something that Oscars do sometimes. There isn’t a clear explanation for why they do this.

It could be that it feels good for the Oscars to make this yawning motion. Or it might have some greater significance that is not understood as of yet.

Final Thoughts

Now you know that there are many potential reasons why Oscars will become sluggish. If your Oscar fish isn’t as active as it should be, it could be experiencing some type of illness.

A sick fish is often going to become lethargic. You might even notice other symptoms such as the fish losing its appetite.

Injured fish will usually become far less active than normal, too. A fish might get injured by fighting with other fish or colliding with something in the fish tank.

Your fish might stop moving as much as it usually does when the water parameters are thrown off. Perhaps the water is too cold or the pH balance of the water might be wrong.

Pay attention to the tank and try to get to the bottom of the situation. You should be able to determine what is wrong and remedy the situation so your fish can get back to normal.

Oscars are hardy fish and they should be okay even if there are minor water parameter issues. Fix problems such as overcrowding or incompatible tank mates as soon as you can if those are what is causing the fish to be less active.

So long as you’re looking after your fish, it’s likely that all will be well. If you need help, you can always contact an exotic veterinarian when you’re unsure of how to proceed.