rm
Passport
- Family
- Oscars and other large Cichlids
- Grows to
- 35 cm (13.8")
- Lives
- 15–20 years
- Temperament
- Predatory
- Care
- Intermediate
- Swims
- Everywhere
- Keep
- One is fine
- Water
- 20–28 °C (68–82 °F)
BrazilPeruVenezuela
Care requirements
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On record for Oscar: adult size, lifespan, minimum tank, temperature, ph, hardness, minimum group, diet, care level, swim level, tank length.
A figure that is not on record is left out rather than guessed. One marked Suggested comes from keeping knowledge rather than a page.
- Minimum tank 284 L / 75.0 US gal
- pH 6–7.5
- Hardness 5–20 dGH
- Diet omnivore
- Tank length 150 cm minimum
Care notes written from general aquarium knowledge, not from the cited sources.
About
Oscars are the fish that behaves like a pet. They recognise the person who feeds them, follow you around the room, take food from your fingers and sulk visibly when they're unhappy. Nothing else in this catalogue has that much apparent personality.
They also grow enormous. A shop tank full of palm-sized juveniles gives no useful warning: an adult oscar is a heavy fish the size of a dinner plate, and it needs a tank most people never anticipate buying.
They rearrange things. Oscars dig, move gravel, uproot plants and shove decor around, apparently for the sake of it. A tank with an oscar in it looks the way the oscar wants it to look.
Tank setup
Buy the tank for the adult, not for the fish in the bag. This is the whole of the advice and the reason so many oscars are rehomed within two years.
Use sand or leave the bottom bare. They dig constantly and coarse gravel gets moved anyway.
Keep decor heavy and simple. Anything light gets rearranged, and anything with sharp edges gets bumped into.
Secure the heater and any equipment. Oscars break things, and a dislodged heater is a genuine hazard.
Cover the tank and weight the lid. They're powerful and they splash enthusiastically.
Feeding
Oscars are carnivores with big appetites and they'll eat almost anything offered.
Feed a quality large cichlid pellet as the staple, with prawn, mussel, earthworm and whole frozen foods for variety.
Never feed live feeder fish. It's the traditional approach and it's a bad one — feeder fish carry disease and parasites, and a diet built on them causes nutritional problems including hole-in-the-head.
Avoid: feeder fish, mammal meat like beefheart as a staple, and overfeeding a fish that will always beg.
Filtration and flow
Over-filter substantially. An adult oscar produces more waste than almost anything else you could keep, and the filtration has to be sized for that rather than for the tank volume.
Change water generously and often. This is the single biggest factor in keeping an oscar healthy long term.
Moderate flow suits them; they're not built to fight a current.
With plants
Oscars destroy planted tanks. They dig up rooted plants as a matter of routine and will tear at leaves out of apparent curiosity.
Attaching java fern or anubias to heavy wood is the only realistic approach, and even then expect damage.
Most oscar tanks are sand, large wood and heavy rock, which is both practical and looks right for the fish.
Health
They're hardy and long-lived when properly housed, and most problems come from a tank that's too small or water that's neglected.
Hole-in-the-head is the condition most associated with them: pits and lesions appearing on the head and along the lateral line. It's linked to poor water quality, high nitrate and a poor diet rather than to a single pathogen.
Watch for a fish that has gone dark, stopped eating and is sulking on the bottom. Oscars show unhappiness clearly, and it's usually worth believing them.
Breeding
They pair from a group, clean a flat surface and spawn on it, and both parents guard the eggs and fry with real determination.
Getting a pair is the difficulty. Oscars choose each other, they're not reliably sexable by eye, and an incompatible pairing turns violent — a male can kill a female he hasn't accepted.
Fry are easy once free-swimming, taking baby brine shrimp and then crushed pellet. The harder problem is what to do with a large brood of fish that all grow into dinner plates.
Tank mates
Avoid94
- Amano Shrimp Oscar reaches 35 cm and will eat adult Amano Shrimp.
- Bamboo Shrimp Oscar reaches 35 cm and will eat adult Bamboo Shrimp.
- Blue Bolt Shrimp Oscar reaches 35 cm and will eat adult Blue Bolt Shrimp.
- Blue Dream Shrimp Oscar reaches 35 cm and will eat adult Blue Dream Shrimp.
- Cardinal Sulawesi Shrimp Oscar reaches 35 cm and will eat adult Cardinal Sulawesi Shrimp.
Only with care13
- Convict Cichlid Oscar is noticeably larger than Convict Cichlid and may bully it or outcompete it at feeding time.
- Jewel Cichlid Oscar is noticeably larger than Jewel Cichlid and may bully it or outcompete it at feeding time.
- Assassin Snail Oscar is a risk to Assassin Snail: oscars and other large cichlids and snails are a pairing to watch.
- Bala Shark Oscar is a risk to Bala Shark: oscars and other large cichlids and sharks are a pairing to watch.
- Bladder Snail Oscar is a risk to Bladder Snail: oscars and other large cichlids and snails are a pairing to watch.
1 species is not covered at all, so they could not be judged either way.