The Oscar Fish Cichlid is native to several countries in South America such as Brazil, Paraguay, Colombia, and Peru.  A species of Oscar can also be found in the Suriname and French Guyana.  The fish is also prevalent in various waterways in Florida USA, although these fish are not native and have either been released on purpose, or have somehow escaped into the wild.

About the Oscar Fish Cichlid. ..

Oscar Fish normally reach sizes up between 11 and 12 inches when kept in optimum conditions such as a large aquarium with good filtration and a healthy diet. It is not impossible for an Oscar to grow in excess of 15 inches, although this is not a common occurrence

It is believed that Oscars can live for 15 years, maybe longer

Aquarium size permitting, you can have as many Oscars as you like.  However remember that the recommended requirements for one adult Oscar is a minimum of 55 UK gallons.  It's easy to do your mathematics, if you want two Oscars then I would recommend a minimum of 125 gallons along with lots of filtration. Please bear in mind that having more than two Oscars could create problems if two of the Oscars decide to form a pair.  Once a breeding pair has formed, they may look upon other fish as a threat, therefore another Oscar may become the target for bullying and ostracising.  It may not happen, it's just something to think about before you decide on getting more than two Oscars. Whatever you decide to do, having more than two Oscars will require you housing them in a tank in excess of 150 UK gallons, I'm not even sure whether these are readily available, you may have to have one custom-made.

An adult Oscar requires an absolute minimum tank size of 55 UK gallons. Two Oscars will require a minimum of 125 UK gallons. You may well read information that contradicts what we say. Some websites suggest that 2 Oscars can be kept in a 75 gallon tank, or even 4 Oscars in a 120 gallon tank. Whereas it may be possible with increased tank maintenance to keep numerous Oscars in tanks of these sizes, we would recommend you stick to what we suggest. Some Oscars can get extremely big and you will have a very hard job maintaining good water quality if you attempt to pack lots of Oscars into an undersized aquarium. How to set up an Oscar Fish aquarium...

The Oscar Fish is not a difficult fish to look after if you give it a suitable environment to live in. You may start having problems such as health issues if you keep your Oscar in an unsuitably small tank or feed it on a poor diet

The directions on fish food normally tell you to feed your fish several times a day and for a given amount of time. Personally I don't take much notice of these directions as the manufacturers are just trying to make you use as much of their product as possible. In the wild fish will not have a reliable food source like they do in your aquarium, they will have to go looking for their food which may result in them going hungry for a day or two. In the dry season when the waters recede fish can often go without food for weeks.

Most people feed their fish every day, sometimes more than once a day. An adult Oscar Fish does not need to be fed on a daily basis, you could quite feasibly feed your fish every other day, or even three or four times a week and your fish would be perfectly okay. I must emphasize that baby and juvenile Oscar's should be fed on a daily basis until they reach adulthood.

I normally feed my fish as much food as they can eat in two or three minutes and then I stop. I don't put a handful of food in, I introduce five or six pellets at a time and I wait until the Oscars have eaten these and then I introduce a few more. If all the Oscars are about the same size I leave it up to them to compete for the food as I believe this keeps them active and alert.

More information on feeding your Oscar Fish..

So long as you have a male and female it is possible to breed Oscars in captivity. Certain factors will determine whether or not Oscars will breed. Water conditions and the temperature of the water will play quite a big role in whether Oscars breed in captivity. Good water conditions & a temperature between 27°C and 29°C will encourage Oscars to  breed
How to breed Oscar Fish..

The Oscar Fish is a semi-aggressive Cichlid which means it could exhibit aggressive behavior to any fish you put in with it. However there are a number of fish that do make good tank mates for your Oscar Fish. Silver Dollars make very good tank mates if added in small groups. Other semi-aggressive Cichlids such as Severeum, FireMouth Cichlid, Blue Acara & Convict Cichlid can be added with caution. Other fish that I have found to be good tank mates for Oscars include Eartheaters (Jurupari) , Plecostomus, Leporinus, Clown Loach, Jade Eyed Cichlid, Syndontis Catfish. Tankmates must be able to defend themselves and compete for food. Adding fish that are too small may well end up as a tasty snack for your Oscar. Please visit our section on tank mates for Oscars Tankmates for Oscar Fish...

People often ask whether they can keep three Oscars together, the answer to that question is you can keep as many Oscars as you like as long as you have got the aquarium to cope with this situation.  However, you have got to remember that if two of the Oscars form a pair, they may well become aggressive during the breeding period.  So whether you've got three, four or even five Oscars, the two breeding pair may well become extremely protective towards their eggs and fry.  If you are serious about breeding Oscars then we would recommend keeping ONLY two Oscars together.

Fertilised eggs are brown in colour. If they remain white then they are not fertilized How to breed the Oscar Fish...

Optimum pH of your water is between 6.0 and 7.0 if you are keeping Oscar fish.  However Oscars are okay in a pH up to 8.0. Remembered that ammonia becomes that much more toxic once your ammonia becomes alkaline, i.e. above 7.0.  Unless you are very confident and know exactly how to make alterations to your pH then we would never recommend trying to alter the pH.  Always check the pH of your tap water, you will then get a good idea of how much it changes once in your aquarium.

This is one of those subjects that crops up from time to time. Sometimes Oscars will suddenly go off their food completely for no apparent reason. It's important that you first test your water to rule out poor water conditions. If everything checks out okay with your water tests then the next thing we normally suggest is to cease feeding for a few days, basically try and starve your Oscar into eating again. This may sound cruel, however Oscars are by nature a very greedy fish and a few days without food will often trigger a healthy Oscar back into eating again.

It may be that they don't like a certain type of food, it is not uncommon for Oscars to completely despise some type of food. Try different types of food and see if they eat. If your Oscar refuses to eat any type of food, even after a few days then please consult us on the community forum and we will try and help further.

Aquarium water should be tested on a regular basis as poor water quality can have a serious effect on your fishes welfare. Test your nitrate before a water change, this will give you an indication of how much water needs to be replaced. Nitrate shouldn't exceed 40 ppm. Ammonia, nitrite & pH tests should be carried out every now and then just to keep a check on things. If your biological filter is healthy then ammonia and nitrite should never exceed 0 ppm.

How to test your aquarium water

The simple answer to this question is yes, water changes are very important when you are keeping fish, especially Oscar fish. If you don't change your water on a regular basis than your water quality will deteriorate which could lead to illness and disease in your fish stock.

It is important that you understand some simple water chemistry such as why nitrate is present in your aquarium. Nitrates are a byproduct of ammonia and nitrite. Whereas ammonia and nitrite are kept under control and removed by your biological filtration, nitrates can only be removed and kept under control by carrying out water changes.

Excessive nitrate levels can stress fish, possibly have an effect on your water chemistry and basically make for a very unhealthy aquatic environment for your fish.

Water changes will also help keep other harmful chemicals at bay, as well as reduce the chances of excessive algae problems. Water changes will also replace minerals that can become depleted.

To get a good understanding of how your filtration system is working I would advise that you get an idea of how quickly your nitrate reaches a level that requires a water change. The easiest way to do this is to test your water at the end of the seven day period. This will give you a good indication of how much water will need to be replaced. If you are feeding too much, have too many fish, or you are using an aquarium that is too small, you may find that your nitrate levels are soaring by the end of the week. In the event of this happening it may well be that you have to carry out more than one water change a week.

Try and get into a routine of carrying out water changes. I can tell you from experience that when you put aside a day and time for tank cleaning, it's a much easier to keep up your tank maintenance regime.

Finally, remember that you may need to give your substrate a clean. It obviously makes sense to do this at the same time you are doing your water change. Fish don't particularly like water changes so to reduce disturbing them too often, carry out these two procedures at the same time.

It is important that you carry out a nitrate test properly and read the instructions fully. This video will show you exactly how to carry out a nitrate test

Having the correct filtration system on your tank is absolutely paramount. Your filter will remove solid waste and the dangerous toxins that are produced by your fish. The Oscar fish it is a large Cichlid that will create a large bioload. In its simplest terms, the bioload is the amount of pressure that is put on your biological filter through ammonia that is produced through a fish breathing, in its urine and solid waste. If you haven't got an adequate filtration system then dangerous toxins will just keep building up until the inevitable happens, your fish dies. So the filtration system you install on your aquarium needs to be able to handle the amount of ammonia and waste your fish will produce.

We always recommend installing lots of filtration, normally double the amount of filtration the tank is rated for. This may seem like a little bit of an overkill but believe me, having lots of filtration will benefit your fish and help keep your tank a safe place for your fish in the long run.

The two types of filter we would recommend are the external aquarium canister filters, or if you want to have the absolute beast of all filtration systems, install a sump filter.  Both these type of filters can hold large amounts of biological and mechanical media filtration.

You can read more about installing your aquarium filtration here

The beauty with using an aquarium sump filter is you can use just about any media you want.  However, we would recommend opting for large media, there's no point in trying to fill a sump filter up with very small particles of media.  When looking for media for a sump filter, try looking in the pond section, this is where you often find the larger type media that is suitable for large sump filters.

Here is a small list of biological and mechanical media that is commercially available and that works extremely well in a sump filter

Scrubbies - these are probably the cheapest option if you are looking for biological media for an aquarium sump filter, scrubbies are made for cleaning dishes, however they make excellent biological media for your sump filter as they have a large surface area for bacteria to grow on.  Three or four packets of scrubbies will give you an enormous amount of biological filtration.  The only disadvantage with this type of media is it will collect a lot of debris and dirt so you will need to clean them every few weeks.

Bio Balls - this type of media is absolutely superb, slightly smaller the ping-pong ball and containing lots of little prongs, they have a large surface area for bacteria to grow on.  1000 bio balls will be enough to filtrate several hundred gallons of aquarium water.  They are excellent as they never get dirty so you don't have the problem of trying to keep them clean like you will scrubbies

Flocor Filter Media - this media is what they call an open cell media and resemble small segments of plastic tubing.  The advantage with this type of media is they won't get clogged with debris and dirt so you never have to worry about water flow being restricted

Alfagrog - this media is extremely porous and resembles small pieces of rock.  Although extremely efficient as biological filtration, this will eventually become saturated with debris and dirt.  My advice when using this type of media is to put it in media sacks so that when you want to clean it, you simply remove the whole sackful of media

K1 Media - this is self-cleaning media, however it needs to be aerated properly.  Once moved by continuous column of air it will give a maximum effective removal rates of ammonia & nitrate.  However at nearly £70 for a small sac, it is very expensive

Filter Media Brush - these are not really meant to act as biological filtration, filter brushes make excellent mechanical filtration and when placed at the very front of your filter where the water enters will catch and stop debris from flowing through the sump filter and clogging up your biological media

Japanese Matting - Japanese matting makes superb mechanical filtration and will collect large debris.  If you've got a large sump filter then feel free to use several layers in one chamber.  Just remember that eventually matting will become clogged with debris and will need to be cleaned.

Filter Foam - this is also mechanical filtration, however it is slightly finer than Japanese matting.  I like using it just before the biological filtration as it will filter out the final bits of solid debris that makes it through the brushes and Japanese matting.  Again, foam filtration will become clogged and will need to be cleaned every few weeks depending on stock levels

You will need to turn your filters off every now and then, normally during maintenance when you are carrying out a water change. It is important that you minimize the amount of time the filtration system is turned off. The beneficial bacteria that live inside your filtration need oxygen to survive. The oxygen is created by the water moving through the filter. Once your filters are switched off oxygen is no longer created, therefore the beneficial bacteria in your filtration system will slowly start the perish.

Exactly how long it takes for bacteria to completely die off it is hard to say, but from my own personal experience I have switched my sump filter off for up to two hours and I haven't experienced any problems.

I have heard of people switching their filters off at night, or during the day to cut down on the noise. This is something you must never ever do, the filtration system must be kept running at all times and only ever switched off for cleaning.  Never let the media dry out for you will lose the bacteria.

New evidence has suggested that beneficial bacteria that live inside your filters can last a lot longer than we ever thought when deprived of oxygen or a service to live on.  Having said this, until there is overwhelming evidence to support this fact we would recommend that you do not turn your filters of for too long at a time.

Hole in the head disease (HITH) affects many different types of cichlids including Oscars. It normally occurs when fish are kept in poor conditions and fed an unsuitable diet.

Symptoms are often small holes developing around the head region. If left untreated, these holes will get larger and deeper and maybe become infected.

Hole in the head disease is both curable and preventable. If your Oscar starts showing early stages of hole in the head disease, increasing tank maintenance and keeping your water in extremely good condition can often clear up early stages of hole in the head disease. Very severe cases may well need intervention with medication. However, regular water changes and a healthy diet are thought to be the main key to preventing an Oscar from developing HITH Hole in the Head Disease in Oscar Fish...

The simple answer to this question is yes of course you can put plants in your Oscar tank, however don't be surprised if the Oscars uproot them, or even just completely rip them to pieces. For some reason Oscars seem to take a dislike to plants and nearly every person who keeps these fish will tell you that they are not successful in keeping the two together.

The Amazon Sword is probably the most successful plant I have ever managed to put in with my Oscars. They are native to the Amazon River so will look authentic if you want to set up an Amazon theme aquarium.They are a fairly hardy plant that will not die on you overnight. Even though the Oscar may be able to operate one of these plants, they can be rerooted fairly easily.

If you keep plants remember that you will have to look after them in much the same way as your garden plants.. If you really want plants then you could try artificial aquarium plants.  Some of these are quite realistic and obviously fairly tough. The Oscar will still uproot them and they will also need cleaning every now and then because they collect algae quite easily.  I have tried keeping plants on various occasions but I gave up a few years ago because it just isn't worth the bother in my opinion

One of the most common infections fish pick up in an aquarium is called "White Spot" or more commonly in the USA, "Ick". White spot is perfectly treatable and if you catch it early enough won't cause any problems whatsoever. We have a well written article on treating white spot that will explain everything you need to do to cure your fish of this parasitic infection

Treating White Spot...

Sand or gravel is what most people use for substrate in their aquariums nowadays. People often ask which substrate is the best to use. Really, it's six of one and half a dozen of the other. When it comes to choosing sand or gravel, you may want to look at the advantages and disadvantages of each type of substrate and what best going to suit your aquarium set up.

Gravel is cheap and readily available from fish stores and garden centres. You can often get a large 20lb bag of gravel for as little as £5. When you buy gravel it will need to be washed thoroughly as it's normally extremely dirty. Gravel is very good at masking debris and dirt such as fish poo. However, solid waste has a tendency to find its way underneath the gravel which if left could contribute to poor water conditions. With the aid of a gravel vac you will need to give the gravel a thorough clean which is often quite time consuming, especially if you've got a big tank. If you are planning on putting plants in your tank then gravel is probably the best option as plants don't really like sand.

Sand comes in lots of different colors and can look absolutely stunning. Sand can be obtained fairly cheaply from garden centres, however some types of different colored sand can be quite expensive, as much as £12 for a 10lb bag. Solid waste doesn't tend to get embedded under the sand like it does with gravel. You'll find that the waste sits on top of the sand where it is much easier to remove with a gravel vac. One drawback of having light colored sand is dirt such as fish poo can look rather unpleasant. Pleco waste is particularly unsightly so if you have got fish that are notorious for producing lots of waste, it might be an idea to opt for a dark colored sand where the dirt isn't so obvious.

Sometimes you may see your Oscar swimming up and down the side of your aquarium shaking, flaring its gills, and even sometimes physically attacking the glass. There is absolutely nothing to worry about, all that is happening is your Oscar can see its reflection I'm probably thinks it's another Oscar. This behavior can also happen if the glass on the bottom of your aquarium is exposed.

There isn't anything you should worry about, this is very common and if you keep Oscars you are more than likely to see it happen at some stage.

When you first set up an aquarium you basically have a tank full of water that will not be able to sustain life for very long.  In order for your fish to survive you have got to cultivate a bacteria colony inside your filtration system.  This bacteria colony will consume and remove all the dangerous toxins that your fish produce, therefore keeping them alive and healthy. This initial process is commonly known as "cycling" an aquarium.  To some people this might sound rather daunting, however it's quite the opposite actually.  Cycling a brand-new aquarium can take several weeks, up to 2 months depending on the size of the tank.  Until the process of cycling an aquarium is complete, your fish will be at risk from toxic poisoning.  Therefore it is vitally important that you understand the importance of cycling your aquarium properly.  Further reading can be found by clicking the link below How to cycle an aquarium...

A water conditioner is used to remove chemicals such as chlorine and chloramine from your tap water.  The chemicals that water companies put into the water to remove bacteria are harmful to fish so you must use a water conditioner every time you carry out a water change.  Most water conditioners neutralise chlorine and chloramine on contact so you can add the water conditioner to your tank and then top it up with tap water after a water change.  If you have got a large aquarium and therefore carry out large water changes you would be wise to shop around for water conditioners and find the best value for money.  Some water conditioners don't really go over a long way, for instance you may have to use 25 mL for every 10 gallons of water, obviously this means that a 200 mL bottle is not going to last very long if you are changing 100 gallons of water.  I use a water conditioner called Prime which goes a long way, you only have to use 5 mL to treat 50 gallons of water.  250 mL of Prime will treat something like 1000 US gallons of water.  So for someone like me who changes 100 gallons of water every week, a 250 mL bottle of Prime that costs £11.95 will last me a few weeks.