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Oscar Fish Species Overview, Care & Breeding Guide

If you want to raise a unique fin buddy, the oscar fish is ready to impress you. It will melt your heart with its cute excited responses to your presence!

The species will intrigue you with its distinct intelligence by remembering close ones’ faces. It’s also extremely popular in the aquarium trade for its non-demanding nature during mealtime.

So, if you want to add one to your collection, keep reading!

Species Overview

OriginWest Amazon and Orinoco basins, South America; Introduced in other areas
Scientific NameAstronotus ocellatus
Common NamesOscar fish, Velvet Cichlid, Red Oscar, Tiger Oscar, Marble Cichlid
IUCN Red List StatusNot Evaluated
AppearanceOval stocky body, symmetrical and standard-sized fins, large and thick lips, eye spots on either side of caudal peduncle
Size24 cm (9.5 in) or more
Maximum Reported Weight3.5 lb (1.6 kg)
LifespanUp to 10-15 years in captivity; Up to 20 years in the wild
TemperamentSlightly aggressive, much more docile than most cichlids, territorial
Tank LevelMiddle-level dwellers
Water Temperature72-82 °F (22-28 °C)
pH Level6.0-7.5
Water Hardness5-19 dGH
Care LevelIntermediate
Minimum Tank Size75 gallons for one adult, 150 gallons for two
Tank EnvironmentSpacious tank with minimal decor
DietOmnivore with carnivorous inclination
Tank MatesOther oscars, cichlids, and similarly-sized top or bottom-dwelling species

Natural Habitat

The oscar fish is naturally found in the western Amazon basins and Orinoco basins, South America. This mainly covers the nations of Brazil, Argentina, Bolivia, Paraguay, French Guiana, Uruguay, Peru, and Venezuela.

This stocky fish inhabits tropical waters with lots of logs and branches to hide from predators.

However, the species has been introduced to many new regions like Australia, South Florida in the USA, India, and China.

It is considered an invasive species owing to its high adaptability and colonizing habits.


The South American fish belongs to the Cichlidae family under the Perciformes order. While its taxonomical name is Astronotus ocellatus, it has many common names like oscar fish, tiger oscar, marble cichlid, velvet cichlid, and red oscar.

Moreover, it has varying local names depending on its origins.

Fun Fact: Oscars are popular as water or river dogs because they wag and shake their tail and head like dogs. They also get attached to their caretakers.


Oscar fish front facing

If you’re keen on getting an oscar buddy, let’s first learn to identify the fish!


An adult oscar is 24 cm (9.5 in) or longer and up to 35.6 cm (14 in) tall. However, the largest recorded one is 45.7 cm (18 in) long and the heaviest recorded fish is 1.6 kg (3.5 lb).


There are about 15 variants of the oscar fish. Some variants also have much longer fins.

The most common ones are tiger oscar, wild oscar, red oscar, black oscar, lemon oscar, and albino oscar. And, of course, with each type, the color and patterns often change.

However, the tiger oscars are called the classics as they are the most popular in the trade. This type has a black body with sporadic orange spots and lines but no pattern from its upper lip to the front of the dorsal fin.


The species has a torpedo-shaped oval body, thick and large lips, symmetrical standard-sized tail and anal fins, and large eyes devoid of patterns around them.

The cichlid usually has a large black spot with an orange ring. The spot is usually at one side at the base of its upper caudal peduncle. It is called eye spot or ocelli, and it confuses predators as to which is the head of the fish.

Some studies have also proven that the eye spots of the oscar fish help them in intraspecific communication during mating and intimidation.

The first gill arch of the fish doesn’t have a lobe. The short gill rakers are thick with multiple denticles. The base of the dorsal and anal fins have dense scales, while the fins have multiple branched rays.

Sexual Dimorphism

In wild-bred oscars, the males are visibly bigger and more colorful than the females. However, such clear distinction is almost impossible in tank-bred ones.

Some enthusiasts try to identify males and females based on differences in mating pairs. But this isn’t a viable method as sometimes, even two females mate. Others say that males have bigger eye spots than females.

The only sign is that the ovipositor in females becomes much more visible before and during mating season. Otherwise, it’s pretty hard to sexually differentiate this species.

Behavior & Temperament

Compared to most cichlids of similar size, oscar fish is known to be much calmer. But in general, the fish is moderately aggressive and can harm smaller species. In the end, this diurnal fish is still a predator.

It is also pretty territorial about its occupied space. According to my experience, sometimes, the fish may also sulk for no reason.


In captivity, the longevity of oscar fish varies from 10-15 years. But in the wild, the fish lives up to 20 years.

Author’s Note: Oscar fish often fades its color according to its surroundings, when it’s distressed, scared, or ashamed of losing a fight with conspecifics, and with age.

Tiger Oscar Fish Care

2 oscar fish in aquarium

Now, if you can’t wait to have this expressive fish in your tank, then let’s prepare the best home for it.

Tank Size

You need an entire 75-gallon tank for one adult oscar fish and a 150-gallon tank for two. To get more, you must upgrade the size by 50 more gallons for each.

The fish needs to stay in a small and dispersed group or at least in pairs. If you get the young fish, you can adjust in a big 75-gallon tank.

Water Chemistry

To keep your pet fish healthy and happy for longer, you must always pay special attention to the water conditions and maintain these levels:

  • pH Levels: 6.0-7.5
  • Water Temperature: 72-82 °F (22-28 °C)
  • Water Hardness: 5-19 dGH
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: Below 20 ppm

Tank Environment

Your next step is to create a suitable environment for the oscar fish to make it feel at home. So, follow these steps.


Soft fine sand is the most suitable substrate for an oscar tank. You can also opt for smooth-surfaced gravel substrates.


The fish is popular for modifying its surroundings. So, it will try to uproot or nibble on most of the plants. So, only add strong rooted plants in the tank. If you want to add plastic plants, ensure they have a weight base.


This cichlid thrives best on low to medium lights. So, make sure you keep the lights on only for 12 hours. You can also place the tank where it gets enough sunlight.


Decorate the tank with bogwood, driftwood, and a few branches. But other than that, make sure you don’t overcrowd the tank. The fish prefers open swimming spaces more than anything else.


The fish can produce ammonia in the tank up to 30% of its own body weight. So, you must use a strong and efficient oxygenating filter to manage the water quality.

Water Flow Rate

Similar to this stocky cichlid’s natural habitat, you must maintain a slow to moderately high water flow rate in the tank with a water turnover rate of 4 times/hour.

Fish Care Tip: The fish is popular for throwing tantrums randomly by thrashing around in the water. It often scares petkeepers. If this happens often, instantly check for ideal water parameters. Don’t worry if everything is fine.

Food & Diet

The fish is a no-fuss omnivorous, i.e., it accepts everything you will feed it. However, it becomes delighted when fed carnivorous feed. So, to upkeep its good health, feed it a high-protein diet with these:

  • Insects
  • Crustaceans
  • Small fish
  • Whitebait
  • Crickets
  • River Shrimp
  • Earthworms
  • Cichlid pellets
  • Plant matter
  • Blanched vegetables like spinach, cucumber, peas, melon, or zucchini
  • Fruits with high Vitamin C concentrations, like oranges or bananas
  • Aquatic vegetation

Make sure you always stay within a limit, as this glutton will keep eating as long as you provide more. Avoid any mammal meat like chicken or beef heart. Never introduce livebearers or small goldfish as food because that may introduce diseases in the tank.

Tank Mates

Oscars may not be as aggressive as other cichlids, but they can be pretty sensitive during the mating season. They are also pretty finicky about their territories. So, you must only go for other oscars.

However, if you want some variety in your tank, you can always go for South American cichlids like these:

However, some pretty rare compatible species with this one are:

  • Bala sharks
  • Plecostomus
  • Red tail sharks
  • Clown loaches
  • Silver dollars
  • Reedfish
  • Black ghost knife fish

Tank Mates to Avoid

The oval cichlid will eat any small species that fits in its mouth, so never house smaller species with it like:

  • Guppies
  • Tetras
  • Corydoras
  • Shrimps
  • Snails

It would be best if you also avoid the following types:

  • Territorial fish from the same water level
  • Aggressive species – Both species may try to injure or even kill each other
  • Any similarly colored fish – Oscar fish might show aggression, thinking it’s a competitor

Common Diseases

With optimal care, the oscar fish can resist most diseases. But it is not entirely disease resistant, so beware and be prepared for the following:

Disease NameCausesSymptomsTreatment
IchProtozoan Parasitic InfectionWhite spots, flashing, drowsiness, appetite lossAdd ich medicine or aquarium salt, raise the water temperature
ColumnarisBacterial InfectionWhite or grey patches fin fraying, drowsiness, appetite lossImprove water quality, reduce stress, add antibiotics
Fin rotBacterial InfectionFin fraying, fin disintegrating, fin discoloration or redness, drowsiness, appetite lossImprove water quality, remove physically injurious decor, add antibiotics
HexamitaProtozoan Parasitic InfectionColor loss, red feces, hemorrhage around its head, large holes or sores, trailing mucus, drowsiness, appetite lossAntifungal medicines
Pop-EyeInfection from injurySwollen and bulging eyes, cloudiness in one or both eyesPerform water changes, add salt or antibiotics, improved diet
DropsyInfection, poor water, stressProtruding scales, swollen belly, redness around vents and fins, ulcers, erratic swimming, no bowels or hard fecesImproved diet, regular partial water changes, add medicines

Quick Tip: Always quarantine your sick oscar before treating it. Since the fish acts fussy and throws tantrums, it will lead to more fights with tank mates.

Breeding & Reproduction

Before you try to breed your oscar fish, know the following:

  • It’s hard to differentiate them sexually.
  • Even if you identify a male and a female, they must like each other to mate successfully.
  • To get a promising mated pair of oscar fish, you must get a school of 6 or more, raise them together, and let them naturally pair.
  • The mating pair must be at least 2 years old to be able to reproduce.

Once you clear this phase, follow these steps.

Tank Preparation

Prepare a large tank (150 gallons) with the dimmest lighting and flat and smooth rocks on the bottom. Since the fish lays its eggs on the substrate, flat stones will help.

Breeding Induction

Once the tank is prepared, introduce the pair to the tank. The species likes to mate during the rainy season, so mimic it with these steps:

  • Perform 20-30% water changes every few days
  • Lower the water temperature by 1-2 degrees
  • Sprinkle dechlorinated water in the tank from above for 5-10 minutes multiple times daily.
  • You can also get this done using spray bars to avoid manual work.

Mating Ritual

When the pair feels ready to mate, they will choose a spawning site and clean it. The female then lays opaque white eggs, which turn yellowish-orange within the next 24 hours. The unfertilized eggs will, however, stay white.

Sometimes, first-time oscar parents often eat their own eggs. But parental care is necessary for the eggs, so don’t separate the parent fish so soon. Usually, if they mate for the second time, they learn to take care of their eggs.

But, if they consume the eggs for the second time, you must separate the parents as soon as they spawn. Instead of the parents, you will have to simulate the fanning of the eggs.

Incubation & Fry Development

The eggs hatch after about 3 days, and the fry consumes its egg yolk. After 4 more days, they become free swimmers. The fry may stay hidden in the substrate until then.

To raise the young fish in the best condition, follow these steps:

  • Feed the fry freshly hatched brine shrimp.
  • Maintain the most pristine water conditions with daily water changes.
  • Use a sponge filter to protect the young fish from getting sucked.

Breeding Tip: The female lays up to 2000 eggs, so if you plan to raise them all, be prepared to house them appropriately. Most amateurs discard this fish when they grow bigger. So, plan carefully on how to proceed.

Quick Buying Tips

  • Buy the fish from a physical pet shop instead of online stores to check for any issues with the Oscar fish’s health.
  • Make sure you observe it closely to check for skin irritation or dull colors.
  • Don’t buy the fish if the aquarium in the pet store has dirty water.

A word from FIA

One of the best parts about having an Oscar fish is that you will give you the joy of having both – a dog and a fish. Its mannerisms will make you want to leave everything and interact with it all day long.

With that said, if you believe you’re a step closer to accommodating this colorful fish, then definitely share this link with other fish enthusiasts. And if you still have some questions, drop us a mail, and we’ll guide you through!