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Why is My Oscar Laying On the Bottom of the Tank? (7 Causes)

Why is My Oscar Laying On the Bottom of the Tank? (7 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.

It’s easy to get attached to your Oscar fish. These are big fish with amazing personalities.

Many people think that these fish are among the best pet fish that you can buy. They’re so much fun, but it’s only practical to own them if you have room for a large fish tank.

Luckily, these fish are quite hardy and they aren’t too hard to care for. They can still have problems in the fish tank, though.

If you notice your Oscar fish is laying on the bottom of the tank, it’s going to concern you. Why would your Oscar be doing this?

Continue reading to learn what causes Oscars to lay at the bottom of the tank. It’ll be better to know what’s going on so you can make changes if necessary.

1 – Bullying Problems

Bullying issues should be looked into as soon as possible. You want to try to get to the bottom of what’s wrong with your Oscar fish.

There’s a chance that the fish might be laying at the bottom of the tank because it’s being bullied by other fish. This can happen for a few different reasons.

It could be that your fish is being bullied by other Oscars. Sometimes this will happen and it’s more likely to happen if you’re dealing with two males.

Generally, it’s not wise to keep two males in the same fish tank. You’d have a better experience with one male Oscar fish and one female Oscar fish.

Males compete over mates, territory, and other such things. One fish is going to be larger, stronger, more aggressive, and dominant over the other.

The fish laying at the bottom of the tank could be a sign of submission. You might want to consider separating the two male Oscar fish so you don’t encounter issues.

Another possibility involves the Oscar fish being bullied by other types of fish. Even though Oscars are pretty large, they can still be bullied by more aggressive fish.

Perhaps you put the fish in an aquarium with other fish that aren’t compatible. You need to take the time to research compatibility carefully before putting together a community fish tank.

If you put Oscars in a tank with bully fish, it can lead to serious issues. In some cases, the Oscar fish might get killed by the overly aggressive tank mates.

There have even been situations where Oscars have jumped out of fish tanks to try to escape bullies. Observe the tank and look for signs of bullying and aggression.

If you see that something is wrong, you can take steps to change the fish tank. Give the Oscar fish its own fish tank or move the bully fish into a different aquarium.

You can’t leave things how they are. If you continue to allow the Oscar fish to get bullied it likely won’t survive.

2 – Poor Water Conditions

Poor water conditions can make Oscar fish lay at the bottom of the tank as well. Paying attention to the water conditions is important.

Many people who buy Oscars as beginners make mistakes. You might not expect that these fish will be as messy as they are.

Oscars eat a lot of food and they defecate a lot in the tank. This fish feces is going to cause the water to get dirty over time.

If you’re not doing regular tank maintenance, the water will start to get nasty. This is going to make it hard for the fish to live a normal healthy life.

You need to make sure that you buy a powerful filter for the fish tank. The filter needs to be able to help keep the tank as clean as possible.

The presence of a good filter won’t make it okay to ignore tank maintenance, though. You still need to clean the fish tank and you also need to do periodic water changes.

Clean the fish tank regularly to try to keep it in good condition for the fish. You should do this on a schedule so you won’t forget.

It’s also best to do regularly scheduled water changes. Weekly water changes of 30% should help to keep the water conditions where they need to be.

Check the water parameters regularly using a pH balance testing kit. This will ensure that you’ll notice any dips so you can correct the pH balance using chemicals.

If you keep the water parameters in the right range, the fish will be much healthier. There’s a good chance your fish is laying at the bottom of the tank due to water quality problems, but you can solve such issues by being a more vigilant fish tank owner.

3 – Sulking

Sulking is something that these fish are known for. They start to act mopey whenever you make changes to the water in the tank.

Specifically, Oscar fish will start sulking whenever you do water changes. This doesn’t mean that what you’re doing is wrong in any way, though.

You see, it’s just a common behavior for these fish. They respond to water changes by sulking.

Sometimes this sulking behavior will involve the fish laying at the bottom of the tank. After some time has passed, the fish will return to acting normal.

There are some Oscar fish owners that suggest doing smaller water changes to try to combat this issue. However, it’s not a big problem and it’s likely better to be thorough to keep the fish tank clean.

Since you want to protect the fish and keep the water quality high, it’s not worth it to be too concerned about sulking. Your fish isn’t likely to continue sulking for very long.

4 – Overcrowded Fish Tanks

Overcrowded fish tanks have the potential to be a huge problem. You see, Oscars commonly grow to be between ten and twelve inches long in captivity.

They’re big fish that need fish tanks that will allow them to live normal and healthy lives. If you attempt to cram them into small fish tanks, it’s not going to work out well.

These fish do much better when placed in aquariums with more than enough space. You want to go as big as you can for these fish without buying an impractically large aquarium.

The smallest aquarium that you can get away with is a 75-gallon fish tank. It’s better to go with a 100-gallon fish tank if you plan to keep two Oscar fish in the aquarium.

Do your best to pick an aquarium that’s large enough for your fish. You also need to consider how much space any potential tank mates might need.

Since Oscar fish can be put in community fish tanks, it’s important to take this into account. Adding too many fish to the tank can become a big problem.

Overcrowded tanks with way too many fish will severely stress the Oscars. You should only put as many fish in the tank as you’ll be able to reasonably fit in the aquarium.

It might be better to have fewer fish than you can comfortably fit. You want the Oscars to feel like they have plenty of room so they won’t behave in unusual ways.

5 – Sickness

It makes sense that Oscars might lay at the bottom of the tank when they’re sick. There are many types of diseases and illnesses that Oscars might have to deal with.

These are hardy fish that generally don’t get sick all that often. That doesn’t mean that they can’t get sick, though.

If your fish is sick, one of the symptoms of the disease that it has contracted might be lethargy. Lethargic Oscar fish might choose to lay at the bottom of the fish tank.

This sort of behavior isn’t that strange at all. It’s not something you want to ignore, though.

Try to see if there are any other symptoms that you can notice. Does the fish have stool that looks unusual?

Can you see any spots on the fish that look different? Does it appear to be gasping for air?

You can use the symptoms and signs to try to diagnose the illness. Sometimes this can be difficult since there are many types of illnesses that have somewhat similar symptoms.

If you’re at a loss, you can always reach out to an exotic veterinarian. A professional can help to diagnose what is wrong fast so you can start treating the fish.

Once you figure out what’s wrong, you’ll need to try to fix the issue. The fish might need medication or it could just need you to fix issues with the tank.

Feeding the fish high-quality food and looking after it could be enough to help it get healthy again. A sickness could be a huge problem or it might be something that you can solve with ease.

No matter what, don’t ignore signs that your fish is sick. If you let things get worse, there’s always the possibility that the fish could die.

6 – Parasites

Parasites can cause fish to be lethargic and lay at the bottom of the tank. There are many types of parasites that Oscars might have to deal with.

The most common parasitic infection is known as ich. This will cause white spots to form all over the body of the fish.

There are also types of worms that can infect Oscar fish. For example, camallanus red worms have been known to infect Oscar fish.

You can buy medications from pet stores that will help you to solve parasitic infection issues. Buy the appropriate medication based on the type of parasite that the fish is dealing with.

It can also be helpful to raise the temperature of the water. Consider raising the water temperature to 82 degrees Fahrenheit until you’re able to get rid of the parasitic infection issue.

Aquarium salt is a good thing that can help the healing process go smoothly. Using aquarium salt as instructed will impede parasites and help the Oscar fish to heal.

Just don’t use more aquarium salt than you’re supposed to. If you pay attention, you can solve problems with parasites without it being a huge deal.

Ignoring the problem could potentially kill the fish, though. That’s why paying attention to the fish and checking on its condition matters so much.

It’s also worth noting that quarantining newcomers is helpful. Sometimes fish that you buy from the store will bring parasites along with them.

This is a common situation that you can avoid by quarantining fish. Have a simple quarantine tank set up for new fish.

Quarantine the fish for four weeks before you put them in the main tank. Some people go so far as treating new fish for ich preemptively.

It’s also wise to quarantine new aquatic plants in a quarantine tank that doesn’t have any fish. This lessens the likelihood that parasites or problematic bacteria will enter the tank by attaching to the plants.

7 – Is the Fish Dead?

Finally, you should check to see if the fish is alive. An Oscar fish might lay at the bottom of the tank if it has passed away.

Perhaps the fish is old and it just died after being in your tank for ten years or longer. These fish can live between ten and twenty years when you care for them well.

The fish could have died due to getting sick, too. There are many things that can cause Oscars to die.

Since they’re hardy fish, they’re not going to drop dead for no reason. It’s unlikely that an Oscar fish will die due to a simple mistake that you made in the fish tank.

Even so, it’s wise to check to see if the fish is breathing. Are the gills moving at all?

You could try to touch the fish with a net to see if it responds. If you get no movement from the fish, it might simply be dead.

Once you’re sure that the fish is dead, you should dispose of it. Don’t leave it in the tank since the presence of the dead fish will negatively impact the water quality for the other fish.

Final Thoughts

Knowing more about why Oscars lay at the bottom of the tank will help you. It could be that the fish has become stressed due to water parameter issues.

You might also be dealing with bullying or some type of sickness. Try to figure out what’s wrong so you can make choices that will help the fish.

If the Oscar fish isn’t breathing at the bottom of the tank, it’s likely that it passed away. Hopefully, your fish is alive and you’ll be able to make changes to help it get back to normal.