Lemon Oscar – A Complete Guide

There are various colors and shapes of Oscar’s species. However, lemon Oscars did not exist naturally, until the start of cross-breeding processes by many aquarists.

Lemon Oscar (Astronotus ocellatus), is a native of South American cichlid.  They have vibrant color, with lemon covering a large part of their body. Thus, the reason for the name “lemon Oscar.”

This article is a compilation of vital about lemon Oscar. Although they are beautiful and peaceful specie, they can lose this attribute if their owner does not care for them properly. Moreover, you should consider adding lemon Oscar to your community aquarium tank.


Unlike the dark-colored tiger Oscar, lemon Oscars have a stunning and eye-catching color variant. They are very appealing to many fish keepers. You should consider introducing lemon Oscars to your fish tank to create a less monotonous scene because it enhances the beauty of an aquarium tank.

Lemon Oscars need a large aquarium tank, with a minimum of 70-gallon size. In setting up your tank, make sure you add large rocks and live or fake plants to the aquarium tank. However, ensure you fix the plants tightly, as lemon Oscars may uproot small or fragile plants. Meanwhile, you can manage this by dropping floating plants in the tank, rather than planting them.

Compare to other cichlids species, lemon Oscar is less aggressive, and they hardly fight for territorial space. Although, they can still feed on almost anything that fits into their mouth. However, you should keep them in a species tank. Whereas, if you are keeping them in a community tank, make sure the tank mates are of similar behavior or trait.

Although a 70-gallon size is fit for keeping lemon Oscar, you should provide a larger tank during the breeding period.  Therefore, 100-gallon tank size is the right choice.

Lemon Oscars are carnivores. They eat many meaty foods like earthworms and small fish. However, they can eat plant matter or sources, such as fruits, vegetables, and algae.

Lemon Oscar Behavior

Lemon Oscars are highly intelligent species. Many aquarists are usually fascinated with Oscar’s level of intelligence. So, they often decide to keep them as pets. Typically, lemon Oscars get familiar with their owner over time. However, this requires the input of the fish owner. For a beginner, it might be quite hard to relate with your fish initially. But you need to be patient with them. Moreover, being a friend with your lemon, Oscar makes keeping them easy.

There are some attitude lemon Oscars show off in certain conditions;

  • Wagging their fin when they sight their favorite food, this also helps fish owners determine the prominent food that should be included in the Oscar diet.
  • They move towards the tank surface when they sight anything that interests them. Whereas, they often play at the tank bottom.
  • Sometimes, they stay at the corner or edge of the tank – This shows they are moody. Mostly, it occurs as a result of an unfavorable environment. Such as poor water quality.
  • They like disarranging their tank. Often, they scatter the tank decorations and remove fragile plants.

Lemon Oscar Temperament

Some people claimed that Oscars are very aggressive, which is not entirely true. Although Oscars indeed eat smaller fish, many other livebearers exhibit this trait as well, like mollies, platies, and goldfish. Moreover, fish are just intimidated based on Oscar’s large size. Whereas, they are more accommodating than betta fish. Oscars can live with another specie if the tank is large enough to allow them to move freely without hindrance.

Lemon Oscar Natural Habitat

Although lemon Oscars are a result of cross-breeding, the ancient forms of Oscars like tiger red or red Oscar have a natural habitat. However, lemon Oscar is quite similar to red Oscar in traits and shape. The significant difference between the two is color. Most cichlids like Oscars originate from m Amazon River. An area with slow and warm water current. Although Oscars are hardy, they can’t survive icy environments.

Lemon Oscar Size

Oscars are often larger in the wild than when captivated. It has been recorded that many Oscars grow up to 14 inches in body size. They are one of the large species among cichlids.

How to Care for Lemon Oscar Fish

Lemon Oscars are easy to keep. They require no strict nor special rules for a successful upbringing. However, there are important determinants to note in caring for lemon Oscar. These include;

Fish Tank Size

 Sometimes, Oscars die at a young age, due to restricted movement. As a fish keeper, make sure you increase the tank size, as your fish grow in body size. Like many cichlids, lemon Oscars require a huge tank.

Tank Requirements

Typically, the measures needed to meet Oscar’s requirements specifically are about its temperature and pH. However, there are test kits for testing if your fish tank meets its requirement or not. These include a heater, filters, and thermometer.

Lemon Oscar Tank Temperature

Lemon fish are susceptible species. They are quick to respond to change in water temperature. A sudden change in water temperature may cause shock to the fish. However, a thermometer will help check if the tank water temperature is constant. Make sure you check the temperature level regularly.

Lemon Oscar pH

The optimal pH level for Oscar is 6.8-7.2 pH. You can keep Oscars within the range of 6.0-8.0 pH. However, make sure you breed them within the optimal range.

Heaters and Filters

Lemon Oscars are messy fish, and you will need to clean up the tank regularly. Also, they are voracious eaters. They can eat almost anything smaller than their mouth. It then releases heavy bio loads into the tank, causing a messy scene. Because of this, you should provide an extensive filtration system for your tank. Also, make sure you install a heater. A file will ease the tank maintenance by removing excess toxins. Whereas, the heater will help regulate the water temperature. However, make sure you install an electrical outlet close to the aquarium tank, because of this electrical equipment. Whereas, having a close electrical outlet will make it easy to regulate the light switch.


A thermometer is an object that helps check the water temperature of your fish tank. However, you must get a thermometer to ensure that your fish meets its required temperature. A sudden rise or fall in your aquarium temperature can cause shock to the fish.

Regular Water Changing

An inadequate water condition is very likely to harm your fish. Bad water is a significant hazard to lemon Oscar’s health. We recommend you change up to 15% of the tank water weekly. However, you can do partial total water change. You will discover how to carry this out, as you read further.

Also, make sure you provide a well-balanced diet for your Oscar fish. Also, stabilize their water temperature often. In general, caring for lemon Oscar involves their tank requirements, water quality, food quality, and water temperature.

Aquarium Tank Cycling

Before introducing lemon Oscar into an aquarium, make sure you cycle the fish tank. Oscars are generally reactive to a high amount of nitrite and ammonia.  Also, ensure you set up the aquarium tank to your test before adding the fish. It will prevent you from frequently having to transfer the fish. Make sure you do proper research about all you need. At this phase, you don’t need to rush. Take your time to learn what to expect and what not to expect. Also, tank cycling allows the growth of useful bacteria, which promote healthy living.

Lemon Oscar Aquarium Tank Maintenance Routine

Having mentioned how to care for your fish tank, we recommend setting up a routine for effectiveness. However, maintenance duration varies based on the severity.

Daily Routine

  • Check if any of the tank equipment is damaged. Repair or replace any damaged equipment.
  • Confirm if the water temperature is at the optimal level. You should adjust if you notice any difference.
  • Notice if there is a behavioral change when you feed them a particular food option.
  • Observe if there are any physical changes related to any disease symptom. You will need to isolate an infected fish.

Weekly Routine

  • Make sure you clean any algae you find in your aquarium tank weekly.
  • Carry out water change by replacing 10-15% of the tank water with clean and chlorinated tap water.
  • Use pH kits to test for nitrite, nitrate, ammonia, chlorine, water hardness, and alkalinity.
  • Clean the filter weekly with extracted water.
  • We recommend you use an efficient material like filter floss, to scrub the aquarium wall.

Monthly Routine

  • Replace up to 25% of the tank water with treated water.
  • Clean or replace carbon, alone, and floss.
  • Check if none of the electrical appliances is disconnected.
  • Remove and clean fake plants and other decorations.
  • Use a gravel cleaner to c=vacuum the aquarium tank.
  • Clean the tank surface to confirm if the lighting is in good shape.

Lemon Oscar Lifespan

Generally, Oscars have a long lifespan. If you care for your Oscar fish properly, it can live up to 15 years,

Feeding Lemon Oscar

Although lemon Oscars are voracious eaters, they are not very picky. However, do not be deceived by their hearty appetite. That is, avoid overfeeding them. Although lemon Oscars need regular feeding patterns for optimal growth, especially juvenile Oscars, make sure you are not making them obese. Avoid overfeeding them, and also prevent making them under malnourished. In other words, provide a moderate feeding pattern.

Lemon Oscars eat small catfish, crustaceans, insects, and small invertebrates in the wild. Sometimes, they feed on seeds, vegetation, and fruits. However, they can be predators to smaller fish. When captured, you must provide your lemon Oscar’s diet that meets their nutritional needs. You should serve them enough pellet, as it gives the needed proteins. However, to provide dietary diversity, you can supplement pellets with live, frozen, and fresh, dried foods.

Foods you can serve your lemon Oscar include; freeze-dried shrimp, live earthworms, peas, fresh shrimp, live mealworms, etc.

Tank Equipment

You may ponder about the necessary equipment you need to set up your aquarium tank. Among several items, here is a list of standard and vital things you will need, to set up your tank:


Often, gravels, sand, and plants serve as substrates for fish tanks. Adding gravel inside your home aquarium will make it appear natural, mimicking the freshwater habitat. However, avoid cleaning the gravel with a detergent. Instead, clean them thoroughly with warm water because detergents can introduce toxic chemicals into the fish tank.

You can use a plant substrate instead of gravels if the tank has some live plants in it. It is because plant substrates are rich in nutrients. This will also enhance the growth of the live plant present in the tank.


Generally, the following items are used to decorate the aquarium tank. This is done to make your aquarium more beautiful. These items are; rocks, plants, caves, castle, tree logs, and live plants. These decorations may serve as hiding spots for your lemon Oscar.

Fish Net

The fishnet is essential for aquarium tank maintenance. Usually, they are used to capture fish and remove unwanted substances in the tank. These include leftover food, dead algae, debris. Fishnets come in various sizes. The size of the fish and the size of the aquarium tank influences the size of the fishnet you will buy. You can purchase a full fishnet if the purpose is for cleaning the tank, and a small size net, if you need it for catching fish.

Another necessary items are;

  • Water conditioner
  • Siphon
  • Light
  • Air pump
  • Tank stand
  • Lid/Hood
  • Air pump
  • Algae removal

Lemon Oscar Tank Mates

If you want to keep your lemon Oscar in a community tank, you should carefully select the type of fish. Although lemon Oscars are peaceful, they are not compatible with all fish types. Also, Oscars are widely known to be territorial. They often fight for what belongs to them. If you place any fish that appear as threats in the same tank with Oscar, you should expect that they will often fight. However, this in turn may harm your lemon, Oscar. Also, you should avoid keeping a smaller fish with Oscars. Oscars are voracious eaters; they will likely eat almost everything that can pass through their mouths. Then, if the tank mate is smaller than your lemon Oscar mouth, you can expect them not to be an exception.

Generally, there are compatible species you should consider. They are;

Jack Dempsey






Other Oscars

You should bear in mind that these fish will likely fight each other when first introduced into the tank. However, you shouldn’t worry much about this. They will get along as time goes on. Nevertheless, you should separate them if the fight continues. Also, lemon Oscars are quite large in body size, the same as the fishes listed above. So, you should provide a tank large enough to accommodate all. Make sure the fishes move freely without bumping into each other. Also, fix a goof filtration system that will quickly get rid of excess waste or bio load.

Tank mates, you should avoid;

Invertebrates like crayfish, shrimp, and snails. These species are fragile and can be quickly eaten by your Oscar fish. Generally, avoid keeping small fish in the same tank with lemon Oscar. Ideally, any fish less than 10inches will serve as snacks to adults or big Oscars.

Lemon Oscar Diseases

Sometimes, Oscars are vulnerable to infections. Whereas, lemon Oscar fish isn’t an exception. The most common disease associated with them is the “Hole-in-the-Head” disease.

Hole in the Head

Hole in the head disease is highly susceptible to freshwater fish like cichlids. Another name for this disease is the Lateral Line Erosion, shortened as LLE.


  • Head Lesions
  • Lethargy
  • White sores
  • Loss of appetite (if left untreated)
  • Death in Severe Cases (due to loss of appetite)


  • Under nutrition – such as vitamin and mineral deficiency
  • Poor water quality – High level of nitrate, nitrite, and ammonia in the aquarium tank
  • Parasitic infection – For example, Hexamita. Which may infect the fish gall bladder, abdominal cavity, kidney, and spleen.
  • Stress – It may be caused by oxygen deficiency, overcrowding, and sudden change in water temperature etc.
  • Age – Older lemon Oscar often has a weak immune system that can’t fight against bacterial infection.


Since lifestyle choices majorly cause the disease, you need first to check the source of the infection, and make adjustments. For example, you can change the tank water, to reduce the degree of toxins present. However, make sure you condition the new water before adding it to the tank. Also, you can correct poor nutrition by providing a diet rich in the essential nutrients.

If the disease persists after carrying out the appropriate measures, then you should treat it with medication. It shows the condition has passed its early stage. However, Flagyl and metronidazole are popularly known to treat hole-in-the-head.

Other diseases that affect Oscars are;

  • Popeye Disease
  • Fin and Tail rot
  • Ich
  • Dropsy

What Food Is Best for My Oscar Fish Growth?

Generally, Oscar fish requires a protein-rich diet for optimum growth. Although Oscars are carnivores, they sometimes eat plant sources.  It is popularly known that Oscars grow at a fast pace. It is not a myth. This is because of its high nutritional requirement, especially juvenile Oscars, as they need a protein diet for rapid growth. However, you should supplement the protein diet with live and fresh foods to create dietary diversity. The primary source of protein for fish food is pellets. However, you can serve juvenile Oscars white worms. Not only is it rich in protein, but it also contains a high amount of fat.

Also, their feeding pattern affects their growth rate. Usually, we recommend that you feed baby Oscars 2-3 times daily. Whereas once daily is suitable for adult Oscars. However, you should decrease the number of feeding to 1-2 daily, when your fish grows to 5-6 inches in body length. In as much as Oscars need a large amount of food for growth, make sure you are not overfeeding them.

Sexing Lemon Oscar

 For a successful breeding process, you should be knowledgeable about lemon Oscar sex. Although both genders have significant similarities, there are slight differences between them. It will be trouble to keep two male genders in a separate tank for breeding. These two fish will fish each other. However, the best time to check your Oscar’s sex is when it’s very close or during the spawning period. Female lemon Oscar posses flat and wide breeding tubes. While male Oscar has a sharp and fine end, it is more convenient to purchase a bra feeding pair from a fish store, as these breathing tubes are only seen during the spawning period.

Moreover, juvenile Oscars are not sexually mature until 14 months. But you can’t be sure the fish will breed immediately. However, some female specie withholds themselves for the first 2-3 years. Also, it is more expensive to raise young Oscars for breeding, than purchasing pairs with previous breeding history.

 Also, make sure you ask for proof of breeding history or proof, if you will be getting the pairs from a fish store.

Breeding Lemon Oscar

Sometimes, fish owners are lucky by perfectly keeping Oscars pair that fit each other as they grow. However, if otherwise, you can still breed your Oscars deliberately. Oscars are a great choice as beginner fish in a home aquarium. Nevertheless, breeding them can be somewhat risky.

Make sure you are fully prepared to manage the breeding result in terms of finances, space, and materials available. Lemon Oscars can release up to 1000 eggs after spawning. Maintaining and housing them will require extra costs from the owner. For example, you will need additional filters, heaters, tanks, air pumps, etc. Also, it will require extensive labor. Moreover, Oscar’s compatible pairs in the same tank will keep mating until exhausted.

Tips to induce Oscars breeding process;

  • Create a smooth surface in the tank, where they can lay their eggs.
  • Increase the frequency of their food. The rule says not to overfeed your lemon Oscar, instead serve it little food at intervals.
  • Slightly increase the tank temperature. As said earlier, during breeding, the tank temperature should fall between the optimum range,
  • Change the tank water regularly. Typically, female Oscars can manage from getting pregnant, if they observe the environment isn’t favorable.

Moreover, if you want to confirm if the pairs you select are compatible, you can place them in a separate tank. If you observe, they fight each other, kindly result in them in the previous tank, and select another pair or replace one of the couples.

Preparing Your Fish for Breeding

Often, aquarists prepare their fish for 1-2 weeks before the pairs undergo the spawning process. Although, we stated that that need to feed them more. But there is food that enhances the spawning process more, for example, like snails, shrimp, earthworms, and feeder fish, including minnows, guppies, and smaller livebearers.

When preparing them for spawning, you can separate the male and female and feed them 4-5 meals per day. It is in contrast to the two times daily feeding of average adult Oscars. However, you may want to keep the parent Oscars together. But ensure you serve the female more food than the male gender. It is for promoting egg development.

Caring For Lemon Oscars Eggs

Generally, Oscars are overprotective. They prevent their eggs from getting harmed. Whereas, the fish owner may even be seen as a threat to them. When you check them, avoid getting too close to the eggs. Touching the eggs or staying close will signal danger to them. Also, the female lemon Oscar often blows some air to the eggs. It is done to prevent the growth of fungi.

Setting up the Tank Fry

Oscars fry requires the same tank to set up the system as adult Oscars, although there are slight differences.

Firstly, you will need a sponge filter and heater to keep cycling the tank. We often recommend fish keepers get a sponge filter for Oscars fry as fry can get trapped inside filters like canisters, hang-on-back. Whereas, the fry will be grounded in the impeller, and flush out.

Another thing you should bear in mind is that the tank nitrate level shouldn’t exceed 10ppm, because Young lemon Oscars are more likely to be infected than adult Oscars.

However, fry tanks vary based on their numbers. They can release up to 1000 eggs or more; you need to provide a large tank that will not cause overcrowding AS overcrowding can cause stress to your fish. Ideally, you should give a 30-150 gallon size for baby Oscars.


Lemon Oscar follows the same care requirement as other types of Oscar. They are easy to keep and friendly. Also, they are a great choice as starter fish. However, it may be quite tricky for a beginner to handle them. It is because of the significant increase in growth rate. Changing their tank size, and replacing with bigger requirements can be somewhat stressful. However, it may be more interesting for an expert to breed lemon Oscars.