Oscar Fish Care: Ultimate Guide to Keeping Oscars

Oscar Fish, Astronotus ocellatus
Oscar Fish (Astronotus ocellatus)

This post may contain affiliate links and we may be compensated if you make a purchase after clicking on the links.

Oscar Fish Care Guide

Oscar fish (Astronotus ocellatus) is a Cichlid from South America, and they are a popular aquarium fish. They’re large, aggressive, and intelligent. Compared to many other freshwater fish that are commonly kept in home aquariums, they are smarter and more affectionate. They will come to the front of the tank to greet you, wag their fins, and beg for food, almost like a puppy. This is one of the reasons they’re nicknamed Water Dogs. Other names that Oscar fish are known by are Velvet Cichlid and Tiger Oscars. The Tiger Oscars’ are known for their striking patterns and coloration. The Albino Oscars are beautiful as well. Whether you’re a novice or an experienced aquarist, this guide will serve as your go-to resource for Oscar fish care.

Oscar Fish Care Chart

To start, here’s an Oscar fish care chart with quick facts:

Common Name(s)Oscar, Oscar Fish, Oscar Cichlid, Tiger Oscar, Marble Cichlid, Velvet Cichlid, Water Dog
Scientific NameAstronotus ocellatus
OriginSouth America, specifically in the Amazon and Orinoco Rivers
Temperature72-80 °F (22-27 °C)
SizeTypically reach 10-12 inches in size
Minimum Tank SizeMinimum of 55 gallons per fish, but a larger tank (75 gallons or more) is recommended for their comfort
Food & DietOmnivores, but primarily eat meaty food like insects, fish and crustaceans. The staple food in an oscar’s diet are cichlid pellets
LifespanBetween 10 and 15 years in captivity on average, and can live up to 20 years under optimal conditions
Water pHOptimal pH level is between 6.0 and 8.0
Tank MatesShould be passive but large enough to avoid getting bullied or eaten by the Oscar, such as other cichlids, catfish, and plecos
BreedingOscars form mating pairs and spawn eggs during the rainy season
Common DiseasesSusceptible to Hole in the Head disease

Oscar Fish Care Tips

Here are the 5 tips on caring for your Oscar fish:

  • Start with a Large Tank: Oscar fish will grow to approximately 12 inches in their first year, and an adult Oscar fish requires a minimum tank size of 55 gallons. They grow astonishingly fast, so it’s best to start with a 55 gallon tank or larger. This will ensure proper growth as well.
  • Get a Powerful Filter: Use a filter that can accommodate water volume, provide adequate oxygenation and maintain water quality. Depending on the size of the aquarium, it is best to use a filter with a capacity of at least 2 times the tank’s capacity. Oscar fish can be messy.
  • Do Regular Water Changes: Maintain high water quality by performing regular water changes. Even if you have a good filter, regular water changes are still necessary.
  • Feed a Varied Diet: Feed high quality pellet food as their staple diet. However, supplement it with fresh vegetables, fruits, and invertebrates. It’s important to provide a varied diet.
3 Tips for Oscar Fish Care #shorts

Oscar Fish Care

There are certain requirements to keep Oscar fish. However, as long as these requirements are met, Oscar fish can be cared for by a beginner as well. The care level is not particularly difficult. In fact, Oscar fish are hardy fish, so they are more forgiving than many other types of aquarium fish. Caring for an Oscar fish would consist of regular water changes, similar to many other freshwater fish in an aquarium. Other considerations while caring for Oscar fish would include understanding proper temperature, water parameters, tank size, tank setup, and more.

Temperature & Water Parameters

The temperature and water parameters in an Oscar fish tank should be similar to their native habitat in the Amazon river basin of South America. Here are the requirements:

Water Temperature: Oscar fish are tropical fish that thrive in warm water. The ideal temperature for Oscar fish is 72-80 °F (22-27 °C). Maintaining this temperature range is important.

Water pH: The optimal pH level for Oscar fish is between 6.0 and 8.0. This range provides a healthy and stress-free environment for the Oscar fish to thrive. It’s important to monitor the pH balance as Oscars won’t do well if the pH balance of the water fluctuates too much.

Water dH (Hardness): Oscars can tolerate a wide range of water hardness levels but it’s recommended to keep it around 12dH – 15dH. They prefer softer water, and water hardness going too high can potentially stress them and lead to health complications.

Ammonia Levels: The safest ammonia levels in an aquarium are 0 ppm.

Nitrite Levels: The safest nitrite levels in an aquarium are 0 ppm.

Nitrate Levels: Nitrate levels for Oscar tanks should be kept below 20 ppm.

Tank Setup

When setting up an Oscar fish tank, there are several tank requirements to consider to ensure the health and happiness of your Oscars. Here’s what to consider:

Natural Habitat: Oscar fish are native to South America, specifically the Amazon River Basin. They typically live in slow-moving waters, often hiding amongst submerged branches and aquatic vegetation. Their natural habitat should be taken into consideration when setting up their tank.

Tank Size: The minimum Oscar tank size is 55 gallons, and a tank size of 75 gallons would be ideal. If multiple Oscars are kept in the same tank, there should be an additional 20 gallons for each additional oscar fish. A proper aquarium size is the important part of their tank setup. It provides the space needed for the fish to swim, and also maintain proper water conditions.

Substrate: The best substrate for Oscars is what mimics their natural environment, such as sand or gravel substrate. Keep in mind that they enjoy digging and will often move substrate around. For this reason, you should install a pre-filter on the filtration system’s intake to prevent fine particles from entering the filter and clogging it up.

Aquarium Filter: A capable filtration system is essential for maintaining water quality. Canister filters are often recommended for Oscar tanks due to their efficiency. The filter flow rate should be 3-4 times the tank volume. This helps mimic the strong water flow of the Amazon River Basin. The filtration system will help maintain water quality and good overall water conditions.

Aquarium Heater: Considering that Oscars require a temperature of 72-80 °F (22-27 °C), they will require heating. A heater with a capacity that is properly rated for the tank size would be good. Once thing to consider is durability. Since Oscar fish are active fish, fragile glass heaters may break. In order to avoid this, aquarium heaters with protective covering or units made with durable material would be ideal.

Lights: Oscars require an aquarium light in their tank. Choose an LED bulb with an adjustable light intensity and/or a blue light feature. The lighting hours should be around 10-12 hours per day.

Décor: Oscars like decor that mimics their natural environment such as driftwood, rocks, and live plants. Cave structures provide a good hiding place as well. Keep in mind that Oscars are known to rearrange their tanks, so ensure any decorations are secure.

Tank Lid: Oscars are known to be jumpers, so a secure tank lid is necessary to prevent them from jumping out of the tank.

Oscar Fish Size

Oscar fish are large fish, and the average size of an adult Oscar is between 10 and 12 inches long when in captivity.

In their natural habitat, they average 14 to 15 inches in size. A large Oscar fish can reach up to 18 inches in the wild

Given their large size, it’s crucial to provide them with an appropriate aquarium size. Providing adequate space, as well as proper water parameters and diet of the fish, will help Oscars reach their large size.


The lifespan of an Oscar fish can vary depending on whether it is in captivity or in the wild.

In captivity, Oscar fish typically live between 10 and 15 years on average. However, some Oscars in captivity are known to live well over 15 years. Their lifespan can be affected by the tank setup, maintenance, diet, and overall tank conditions. The level of aquarium care can have an impact on fish heath, so it is no surprise it would affect their lifespan as well. Of course, the genetics of the fish is a contributing factor as well.

In the wild, Oscar fish typically live between 10 and 20 years, with an average lifespan of 18 years.

Food & Diet

Oscar fish are omnivores, which means they eat both plant and animal matter.

Their diet in the wild consists of a variety of foods, including other fish, crustaceans, insects, other small aquatic creatures, aquatic vegetation, fruits, and nuts.

What Oscar Fish Eat in the Wild #Shorts

In captivity, their diet should be diverse as well in order meet their dietary needs as an omnivore.

First, high quality cichlid pellets, such as Hikari Cichlid Gold Floating Pellets, should be the staple food for Oscar fish. The pellet foods are specifically designed to meet their nutritional needs, and contain a mix of proteins, carbohydrates, fats, and essential vitamins and minerals.

Next, other foods such as live foods, fresh foods, vegetables, and fruits can be fed to supplement the diet of the Oscar.

Live foods you can feed would include crickets, mealworms, feeder shrimp, and earthworms. If live foods are not readily available, freeze dried fish food is great as well. They provide comparable nutritional value in a much more convenient form. Freeze dried blood worms, brine shrimp, river shrimp, krill, or mealworms may be suitable depending on the size of the Oscar.

Fresh foods you can feed would include shrimps, scallops, mussels, and tilapia. Many of these seafoods are available in their frozen form. To prepare it for feeding, be sure to thaw it and cut into appropriate sizes.

Vegetables you can feed would include spinach, peas, cucumber, and zucchini. Some vegetables may be too hard for the Osars to eat. Boiling or blanching the vegetables may help Oscars eat them.

Fruits you can feed would include bananas, apples, mangos, and watermelons. Many of these fruits are great sources of vitamin C, which is important for the Oscar’s health.

Feeding Schedule

When it comes to the feeding schedule of juvenile and adult Oscar fish, they have different feeding requirements:

Juvenile Oscar Fish should be fed more frequently than adult Oscars. You should feed them two to three times a day. The key is to feed smaller portions more frequently. As they mature, the frequency can be reduced.

Adult Oscar Fish can be fed less often than juvenile Oscar fish. For adult Oscars, feeding once a day is sufficient. In fact, mature Oscars may be fine being fed only every other day.

You should feed an amount of food that your Oscar fish can consume in one or two minutes. Always remember to remove the excess, uneaten food, because it will pollute the water.

Oscar Fish Feeding #shorts


Oscar fish require regular maintenance and care. Regular water changes, about 20-25% weekly, are essential to remove toxins and maintain water quality. Regular health monitoring is necessary to observe any signs of stress or disease. Changes in behavior, appearance, or eating habits could indicate a health issue.

Fortunately, Oscar fish are hardy fish. Therefore, as long as regular maintenance is provided, most major issues would likely be avoided.


Breeding Oscar fish is a fascinating process that requires careful planning and preparation. Here’s a step-by-step guide on how to breed Oscars:

  • Select a Healthy Breeding Pair: The success of breeding Oscars hinges on the robust genetics of the breeding pair. Mature Oscar fish between 12-18 months old exhibit the best breeding behaviors and health. Choose Oscar fish with vibrant, consistent colors, blemish-free skin, and clear, alert eyes to ensure optimal genetics. Pairs displaying synchronized swimming, mutual nipping, and shared territory indicate compatibility. Avoid inbreeding by breeding unrelated Oscar fish to minimize genetic issues, ensuring healthier fry. Typically, a male Oscar fish, being 10-15% larger than the female, yields better breeding results. Remember that Oscars can be picky when choosing their mates, so this process may require patience and multiple attempts.
  • Set Up a Suitable Breeding Tank: Creating an ideal environment is paramount for Oscar fish breeding. A separate breeding tank minimizes disturbances and protects young ones. A minimum of 75-100 gallons is required for a breeding tank.
  • Maintain Optimal Water Conditions: Specific water conditions can make or break the Oscar fish breeding process. A stable temperature of 77-80°F (25-27°C) induces breeding behaviors in Oscar fish. Achieving a pH range of 6.5 to 7.5, leaning slightly acidic, enhances the chances of Oscar fish breeding success. Replace 25-30% of the tank water every week, ensuring Oscar fish experience a clean environment, free of toxins. In their natural habitat, Oscars breed during the rainy season. In an aquarium setting, you can mimic this by doing frequent water changes.
  • Spawning: Oscars are difficult to sex unless you observe them spawning. As a word of caution, Oscars will “test” each other before the spawning and if one partner does not pass the test, he or she may end up dead.
  • Fertilization: After successful spawning, fertilization occurs. The female Oscars lay eggs and the male fertilizes them. It’s also worth noting that survival of offspring is only around 25%, so don’t be discouraged if your first few attempts aren’t successful.

Common Diseases & Health Issues

Oscar fish, while hardy, can still be susceptible to various diseases and health issues. Here are some of the common ones:

  • Fin Rot/Tail Rot: This is a bacterial infection that affects the caudal fins (tail fin) and other fins of the fish. It’s caused by various bacteria that are often present in the fish tank. Healthy fish generally don’t have much to fear, but when they become stressed or have compromised immune systems, this can become a problem. Poor water quality, such as not cleaning the fish tank well or not doing water changes, can stress the fish and make them susceptible to infections.
  • White Spot Disease/Ich: This is a common parasitic ailment among Oscar fish. It’s caused by a tiny protozoan that attaches to the fish’s body. Symptoms include tiny white spots across their body and fins, scraping their body against objects, erratic swimming, clamped fins, and breathing difficulties.
  • Hole in the Head Disease: This is a serious problem that can be fatal if left untreated. The exact cause hasn’t been determined but one possible culprit is the flagellate parasite Hexamita.
  • Parasitic Infections: Oscar fish can also be affected by internal parasites such as planaria, roundworms, and nematodes. Deworming Oscar fish can be done using specific deworming medications.

In all cases, maintaining good water quality and regular monitoring of your Oscar fish’s behavior can help in early detection and treatment of these diseases. If you notice any signs of these diseases or illnesses, such as your Oscar fish spending more time at the bottom of the tank or changes in their fins, it’s recommended to take action as soon as you can.

Tank Mates & Behavior

Oscar fish are known for their aggressive behavior towards other fish, which is not unusual among cichlids. They are often categorized as “mildly aggressive” and their aggression is usually manageable. However, they can become quite territorial and may attack other fish that enter their territory.

Due to their aggressive nature, Oscar fish are not typically recommended for community tanks. They are better suited to tanks with large, peaceful fish that won’t get in the way of the Oscar fish. It’s important to note that Oscar fish will eat smaller fish that fit into their mouths, so tank mates should ideally be quite large to avoid being consumed.

Here are some species that are often considered suitable tank mates for Oscar fish:

  • Convict Cichlid
  • Jewel Cichlid
  • Jack Dempsey
  • Green Terror Cichlid
  • Firemouth Cichlid
  • Sailing Pleco
  • Common Pleco
  • Silver Dollar Fish

It’s crucial to remember that each type of fish needs to be compatible with the Oscars as well as the other fish in the tank. Therefore, careful research and consideration are necessary when choosing tank mates for Oscar fish.

Careful consideration is needed even when adding other Oscar fish into the same tank. While Oscars can live alone, given the right conditions, it is also possible to keep two to five Oscar fish together. Oscar fish are social creatures, so they enjoy being in pairs or small groups. However, Oscar fish require a lot of space to thrive. A full-grown Oscar typically needs a 55-gallon tank or larger. For every additional Oscar fish, you need to add at least 20 gallons to the tank. If you have limited space, just stick to keeping one Oscar fish. Additionally, you should be cautious of keeping three Oscar fish together, as two of them may bond together and dismiss the third one.

1 thought on “Oscar Fish Care: Ultimate Guide to Keeping Oscars”

Leave a Comment

Your email address will not be published. Required fields are marked *