Oscar Fish Aquarium Setup, Live Plants, Filtration, Tank Lights, Heater, Care Guide, Maintenance & More:

Oscar fish is an aggressive species, & it could prove deadly to the other fish that you have in your aquarium. It is recommended to find suitable tank mates for Oscars if you want to keep Oscars in a community tank.

They look very attractive & are available in a variety of beautiful colors, & they are quite genius.

Only experts can take proper care of Oscars. They like an omnivorous diet so it is simple to feed them because they eat almost anything.


Oscar Fish Origin:

Oscars belong to the Cichlidae family. Most of the cichlids originate from Africa or South America. Oscars originates from South America.

Oscars are able to live in the aquarium for about 20 years.

Oscar Fish Aquarium Setup
Oscar Fish Aquarium Setup

Oscar Fish Aquarium Setup:

Oscars are both aggressive & territorial, so think before adding them to your aquarium because they could be dangerous to other fish.

They don’t fear fighting & will fight any fish that enters the area they are guarding. If they are mating or feeding, they can be aggressive too.


Swimming Behavior of an Oscar Fish:

They like to swim in the mid-levels of the aquarium, & they swim more. They can look for food in the bottom of the tank. They have another problem of uprooting live plants while finding food, so make sure everything is fixed.


Oscar Fish are Territorial:

Oscar fish can form a large or small territory depending on their size & level of aggression. They will chase other fish that enter their territory.

If you provide enough room for the fish to form its territory & setup things well inside your aquarium, then it could lower their aggression.

Design a separate aquarium for Oscars because they could be aggressive towards other species.


Care Level for an Oscar Fish:

Caring for Oscar fish is not a simple task. Those who have been caring for other fish for a few years can take care of this fish. Oscars are not recommended for beginners. If you start caring for Oscar then they will teach you to take care of other Cichlids too.

Oscar Fish Care Guide & Maintenance
Oscar Fish Care Guide & Maintenance

Oscar Fish Aquarium Care Guide:

Oscar fish grow quickly in aquariums. They grow approximately one inch in a month until they are fully mature. Keep Oscar fish in at least 55 gallons of aquarium or otherwise they will be stressed, & could get sick & die.


Maximum Size of an Oscar Fish:

Oscar babies are very little like other tropical species but they can reach a length of 1 foot.

Due to their large future size, it is recommended to setup a large tank even if you introduce Oscar babies to the aquarium.


Maximum Lifespan of an Oscar Fish:

Oscars can live a life of up to 20 years in your aquarium if cared properly.


High Maintenance is Required for an Oscar Tank:

They are very messy & need more maintenance than many other types of fish. They poop too much so need a quality filter to address this issue. If you keep them in a smaller aquarium then they will need high maintenance & frequent water parameter tests.


Recommended Water Conditions for an Oscar Fish:

Despite being the Don of the aquarium, Oscars are sensitive fish when it comes to water conditions, & they are prone to a variety of illnesses. Keeping them in clean water will not stress the fish, & it will enhance the immunity of Oscars.

In this video I can help you in setting up an Oscar fish tank:

How to setup a Planted Oscar Fish Tank Aquascape

Ideal Water Temperature & pH for an Oscar Fish:

Keep Oscars in temperatures between 75 to 80 F, & the preferred pH range for this fish is between 6 to 8.


Ideal Water Hardness for an Oscar Fish:

Oscars can live in a wide range of water hardness but the ideal water hardness for this fish is about 12 dH to 15 dH.


Bad Water Conditions Stress an Oscar Fish:

Oscars are stressed due to alteration in tank temperature along with rise of ammonia levels in the aquarium water. Provide a better filtration for the fish & setup a quality tank heater with a thermostat for keeping the same temperature throughout your aquarium.


Maintain Same Temperature & Keep Ammonia Levels in Control in an Oscar Aquarium:

If you can’t keep the accurate temperature & your aquarium water has increased levels of ammonia then it could stress your Oscars, & they might lose their color, eat less, & will not be living happily in their aquarium.

Test your aquarium water from time to time to keep the water parameters controlled.


Does an Oscar Fish Like Living in a Planted aquarium:

Oscars do not need better pre-settlement of tanks because they like setting up their aquarium on its own so only introduce a few live plants, rocks & stuffs, & allow them to re arrange their aquarium.


Oscar Fish are Moody & have Unpredictable Behavior:

Oscar fish are unpredictable & it depends on their mood, how they react towards their environment. At times they will love the plants but the next moment they could be aggressive, & will be uprooting them & throwing them away in a rage. Only introduce hardy plants in Oscar’s aquarium. Keeping floating plants are good in Oscar’s tank because they provide a greenish appearance to their environment.


Best Live plants for an Oscar Aquarium:

Best live plants to keep in the Oscar fish aquarium are:

  • Java Fern
  • Java Moss
  • Salvinia Natans


Only Keep Live Plants in an Oscar Fish Tank that have Similar Requirements:

Only add live plants to Oscar’s aquarium that have similar needs. Do not keep plants that need warmer water than your Oscars. Do not just add a plant to Oscar’s tank but first do a net research to find a compatible plant for Oscars. Many plants have similar needs as Oscars so you will find a large variety of compatible plants.


Oscar Fish Need Frequent Water Changes:

Oscar fish needs frequent water changes to keep the water parameters controlled. Also, adding fresh water will add minerals that the fish need.


Aquarium Filtration in an Oscar Fish Tank:

It is very crucial to learn how your aquarium filters work & how to setup filter media in a filter. Every filter can do both mechanical & biological filtration, but chemical filtration is optional & not every filter offers space to keep chemical filtration media. Mechanical filtration uses foams & sponges, chemical filtration uses activated carbon, & biological filtration uses bio media.


Mechanical Filtration:

Mechanical filtration is carried out using sponges or foams. It can trap physical particles in the water such as fish poop, excess food, dead leaves, dirt & other debris. If these waste particles are not collected, they will release harmful chemicals that will be toxic to the aquarium fish. Waste particles will be sucked by the filter using a pump & they will pass through mechanical filtration media that will remove every physical particle from the water & will allow clean water to flow through the biological filtration. Mechanical filtration uses three types of media: coarse, medium & fine foams / sponges. Coarse foam will trap all big waste particles, while medium & tiny particles can flow through it. Medium foam will trap all medium sized particles while fine foam will ensure that every tiny particle is stopped.


Q) If fine foam can even collect large & medium particles, then why do we add coarse & medium foams?

A) Because if large & medium particles are trapped in fine foam then it will clog the media very quickly & will soon reduce its cleaning efficiency.


Order of Mechanical Filter Media:

Order of filter media is very important. Coarse foam should come first followed by medium & fine foams because coarse foam will take care of every large particle, while medium sized particles will be stopped by medium foam, & fine foams will take care of tiny little particles.


Biological Filtration:

Biological filtration is very important in all types of filtration. Ammonia byproducts released from fish waste are wiped out by biological filtration. Biological filtration is natural because every aquarium contains good bacteria that are produced after the nitrogen cycle. It is very important to cycle your aquarium before adding fish to it so that useful bacteria are thriving in the aquarium. Beneficial bacteria need oxygen for survival & it can’t live outside water. Large surfaces provide room to grow heaps of beneficial bacteria. Biological filter media has an outer surface, & tiny little pores that add more room for the growth of beneficial bacteria.


Nitrifying Bacteria:

Nitrifying bacteria grows in oxygen rich places & they grow everywhere in the aquarium & especially on the large surfaces of bio media. Nitrifying bacteria breaks down ammonia into nitrites, & further into nitrates. Nitrates are less toxic than nitrites, & nitrites are less toxic than ammonia. Nitrates are still toxic to fish & presence of high levels of nitrates could be fatal. Nitrifying bacteria can’t wipe out nitrates from the aquarium water.


Denitrifying Bacteria:

Denitrifying bacteria is used to wipe out nitrates from the aquarium. Not every bio media is ideal for the growth of denitrifying bacteria because they grow in oxygen less places like in the tiny little pores of bio media. These pores are very tiny & it is difficult to see them without using a microscope. These little holes are air free & provide the ideal environment for the growth of heaps of denitrifying bacteria. Certain bio media allows the growth of both nitrifying & denitrifying bacteria such as ceramic rings.


Chemical Filtration:

Activated carbon is used as chemical filtration media. They can wipe out various toxins from the aquarium water. They are used to remove medication that has treated the fish, & now the leftover medicine needs removal. Other purposes of chemical filtration include treating water smelling. Overtime chemical media will be fully saturated & in that case, toxins that it has accumulated will be released back in the water so it is your choice if you want to use chemical media or not. Chemical filtration media is not necessary.

For detail information about Chemical Filtration, check out this article: Is Chemical Filtration Required


Which Filter is Best for an Oscar Fish Tank:

Oscars need a large aquarium, & if it will need multiple small filters & just one big aquarium filter. I would suggest you use a canister filter because it is designed for large aquariums.


Canister Filter is Best for an Oscar Aquarium:

Canister Filter is Best for an Oscar Aquarium
Canister Filter is Best for an Oscar Aquarium

Canister filters are able to provide three types of filtration: Mechanical, biological & chemical filtration. Canister filter can filter large volumes of water & it is located outside an aquarium so it is not taking up the space inside an aquarium water. Water is sucked from the aquarium via an inlet hose. Water flows to the bottom of a canister filter using an internal tube, & then it rises upward through the filtration media. First it hits mechanical filter media, then chemical (chemical filter media is optional) & biological filter media. A pump is attached to the outlet hose then pumps clean water back to the aquarium.

If you want to know how to Setup a Canister Filter then Read this article: How to Setup a Canister Filter


Advantages of a Canister Filter in an Oscar Aquarium:

Other than filtration, canister filters can circulate & aerate water. They are designed for large aquariums because they clean lots of water, & they are energy efficient too. Some Canister filters also come with UV sterilizer that can wipe out harmful microbes in the aquarium water.


Problem with Normal Filters in an Oscar Aquarium:

Oscar fish are messy & they make lots of poop, & it is difficult for a normal filter to address this problem. I think that if you are keeping one Oscar in a 55-gallon aquarium then use a filter that is rated for a double sized aquarium such as around 100 gallons of water.


Best Heater for an Oscar Fish Tank:

Oscar can live in an aquarium that has a lower temperature of up to 21 Degree Celsius. The upper temperature limit is 30 Degree Celsius. If you want to know the ideal temperature for an Oscar then it is 27 Degree Celsius. Oscar is a messy fish & they mess around with almost anything that you add to their tank. They usually don’t like a tank heater. Oscars have the habit of breaking heaters so find the one that is strong.


Best Lights for an Oscar Fish Tank:

Oscar fish can live even in the dark, & any light is fine for their aquarium. Many lovely colored fish do not look beautiful in the absence of quality light. However, many Oscars look dull & they don’t show beautiful bright colors in the availability of strong light.

Tank lights could also depend on how you want to watch your Oscar fish. Many aquarists want to watch their fish clearly so they need strong lights.


Choose Lights that meet the Requirements of Live Plants:

If you are adding live plants in your Oscar’s tank then choose lights based on the requirements of the plants. Live plants need light for photosynthesis so light must hit the plants located at the bottom of the aquarium. If your aquarium water is dirty then lights will not be able to penetrate through it & won’t reach the bottom with high intensity. Also, if you are keeping floating plants then they are much closer to the lights.


Which Lights are Best for a Planted Aquarium:

Choose lights that spread in the aquarium so that it could reach the plants that are not directly below it. Many LED lights offer high intensity & spread so if your tank light is shorter than the entire length of the aquarium then still plants at the corner will be able to receive direct light. Not every plant is hungry for the light because many of them do not need direct light. They can grow even in shadows. If you are keeping other fish & live plants in Oscars’ fish tank then make sure you choose the lights that are best for every fish & live plant. LED lights are more energy efficient than any other aquarium lights.


How much Lighting in Enough for an Oscar Aquarium:

Do not leave your aquarium lights on for over 12 hours a day. Sunlight in the tropical areas is illuminated for 12 hours in a day so if you want to mimic a natural day / night then do not leave your lights on for over 12 hours in a single day. Oscars originate from the tropical areas so mimicking that environment is ideal for the fish.

If you want to know which Light is Best for your Aquarium then read this article: Comparison of LED vs Other Aquarium Lights


Disadvantages of Aquarium Lights in an Oscar Aquarium:

You will witness algae bloom if you add high intensity tank lights or if your tank lights are turned on for longer periods. Algae needs lights for growth & they will magically appear in the tank if your aquarium is illuminated with strong lights. Do not keep your aquarium in direct sunlight because it will cause algae spikes.


Top Substrate for an Oscar Fish Tank:

It is good to use substrate in Oscar’s tank especially if you are keeping live plants. Add a thick layer of substrate because Oscars have the problem of uprooting plants. Adding sand & gravel is fine for an Oscar tank. They are available in various colors. Live plants should be fixed hard in the substrate if you want to stop Oscar from uprooting them.


What are the Benefits of Wood in an Oscar Fish Tank:

Wood is good & adding it to a fish tank can offer a natural appearance. Wood comes at a cost & large wood is very expensive. Choose the one that does not rot when submerged in water. Boil the wood before adding it to the fish tank so that every impurity is removed. If you are keeping other fish in an Oscar’s aquarium then they could use wood & other hiding places for hiding from the Oscar fish. Many aquarists attach plants like Java Fern & Java Moss to driftwood.


How to Prepare Driftwood for an Oscar Aquarium:

Add driftwood to an aquarium but remember driftwood will release tannins once submerged in water. Boiling driftwood will wipe out tannins. When you boil driftwood, then you will observe that the water in the pot will look like tea. Change the water & boil driftwood again in clean water, & keep changing water until water color does not change.

If you want to learn how to boil a driftwood then check out this tutorial: How to prepare driftwood for an aquarium use?






Care Level



Aggressive / Territorial




Up to 20 Years

Maximum Length

Up to 12 inches





Minimum Aquarium Size

55 gallons

Aquarium Setup


Tank Mates

Large, Passive Species

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