Are Oscar fish freshwater?

Oscar fish, also popularly known as the tiger Oscar fish is a cichlid that is known for its aggressive territorial behavior and bright colors. This fish stands out in its class as a favorite amongst aquarium keepers. One of the questions that have been recurrent about this fish is on what sort of water it thrives in. Freshwater or seawater. This article aims to clarify what sort of water the Oscar fish can survive and thrive in.

Are Oscar fish freshwater fish?

Yes. Oscar fish are native to the Amazonian River and a host of other freshwater rivers in the Americas, and some other places including Asia. Oscar fish are kept in freshwater even when they are in captivity. They cannot tolerate seawater at any level at all.

Oscar fish enjoy freshwater. But there are other details that their water must possess for them to be able to live in it. Oscar fish are very peculiar animals and even the slightest deviation from their requirements could harm them. It could also prove to be fatal. You are therefore encouraged to read right in so as to find out everything about Oscar fish water preferences.

Oscar fish water pH

Oscar fish In the Amazonian rivers and basically everywhere they can be found in the wild prefer a water pH of around 7.2. the water pH of these particular fish remains between 6 and 8 all the time.
Fish keepers worldwide agree that one should always aim to replicate the natural habitat pH of their fish at all times.

pH affects the fish in a way that humans may not understand. It is the pH of the water that determines how toxic it will get when ammonia gets into it. Bad pH can increase the likelihood that the fish will succumb to the ammonia and die.

You can alter your Oscar fish water by sprinkling tiny amounts of salts in it. Try not to make sudden changes though as this could be counterproductive

Oscar fish water temperature

Oscar fish thrive in the warm waters of the Amazon River Basin. The water in these areas is stable around 74 degrees Fahrenheit (23.5 degrees Celsius).

When you keep Oscar fish as pets, it is important to keep their water temperature at about 77 degrees.

This is about 25.– 27 degrees Celsius. You should however ensure that that is stable at 81degrees at all times.

Things that can make Oscar fish water dirty faster

There are factors that can make you need to change the fish water more than the ideal twice weekly. Some of these can be due to ignorance or carelessness.

  • Food: Oscar fish eat a lot of other animals. These can produce ammonia if there are leftovers in the water. The food can also sink to the bottom of the tank and mix up with the substrate. Try as much as possible to gauge your fish’s appetite before feeding him. It is also important to feed them according to their age and what they can handle so that there are no unnecessary leftovers in the tank.
  • Poop: You could have a frequently dirty and stinking tank on your hands if your filtration system is not good enough. The Oscar fish poops a lot and this means that they need to have that poop removed from their tank fast. A good filtration system will help with that.

How often should I change Oscar water

Oscar fish are very messy animals. It is important to keep them clean and healthy. One time in a week water change routine is just great for them. But it would also be cool to aim about three times in two weeks. This is about five days intervals.

Oscar tank water pressure

Oscars enjoy medium to strong water flow. This is reminiscent of the water they are used to in their natural home in the Amazonian rivers.

Oscar fish can cope very well with strong water currents. The fish will remain happy and healthy as long as it is able to swim comfortably.

Ammonia and its perks

Oscar fish and every other fish produce ammonia as a waste product. This chemical is very toxic and can be fatal when it is unionized. The Oscar fish will become sensitive and may fall sick as the water loses its clean clear form and becomes contaminated by ammonia.

If your Oscar water pH level is high, it will make the ammonia toxic. The ammonia will become toxic enough to be fatal when the water pH reaches a pH of 8.Oscar fish keepers should do water tests for pH levels. You can do this kind of test with the help of an ammonia kit.


Nitrite is much less toxic than ammonia. It is however dangerous and could be fatal too. The by-product of this chemical, nitrate can cause algae to grow in Oscar fish tank and algae could cause your Oscar fish to fall sick and die too.

You can keep the water free of nitrate and algae by changing it as often as possible. You could also test the water often to check toxicity.

Oscar water filtration

We have already established that Oscar fish are sensitive to even the slightest water changes. A high quality filtration system is therefore needed to keep the fish healthy at all times. Now Oscar fish are large fish. This means that they also produce a whole list of fish poop. You will need to place a lot of focus on biofiltration.

Examples of filters that you could use are the:

  • canister filters and
  • HOB filter will do a good job of keeping the tank nice and clean.

The target is that the filter should be able to turn the water over four times every hour.

Why you should never use chlorine

Chlorine is a chemical that is often added to water to kill bacteria and make it safe for human consumption. This chemical in itself is a very toxic and harmful gas. It could harm fish and even humans. The combination of this chemical and ammonia make a very lethal substance that will kill fish in a very short time.

Under no circumstances should you be tempted to disinfect the fish water or tank with chlorine.

You can take your care a step further by using dechlorinator each and every time you use fresh water for your fish. This will not only remove chlorine, but it will also remove all trace metals like lead and mercury from the water.

You can do a chlorine test just to be sure or if you have the slightest doubt that you have dechlorinated the fish water properly.

Oscar fish and rain

Oscars love when it’s raining. Not just because it is freshwater. But also because it seems to affect their reproductive cycle. Frequent and heavy rains could mean that Oscars will reproduce more often and with more offspring each time.