Oscar, Astronotus ocellatus

OSCAR

Astronotus ocellatus

GENERAL INFORMATION

This is 'Slayer' the Oscar. He is well named, having attacked several people and frightened many more. His bite draws blood, and he hates people invading his tank with their hands.

DESCRIPTION

A heavily built fish having a grayish body and bright orange marks. Has a large mouth, bulging eyes and paddle shaped fins. Not a pretty fish, but it has redeeming qualities.

SIZE

30 cm and heavy.

INTERESTING FACTS

Although they come from the Amazon basin, there is a feral population of Oscars in Florida USA.

Oscars are thought to be one of the most intelligent aquarium fish.

Oscars can be trained pull levers or ring bells when they are hungry.

APPEAL

My Oscars are big, ugly and nasty. They are also my favorite fish. Their intelligence and personal character is their big winning point. Those fish will actually make eye contact with me when they want to be fed. Oscars are also good parents, both parents guard the eggs and then the fry when they hatch, unlike most fish which just eat their own fry.

AVAILABILITY

Generally available from most aquarium shops.

MAINTENANCE OF CAPTIVE SPECIMENS

'Slayer' the Oscar attempting to look cute.

SUITABILITY

Advantages:

Happy in a standard aquarium (120 cm or more).

May fight with its own kind but Oscras are built for it.

Defends itself if harassed.

Easy to feed.

Not particularly sensitive to water quality.

Happy in a tropical tank.

Disadvantages:

Grows to a large size.

Will eat other fish that are smaller.

Is territorial and may attack other fish.

Eats almost anything.

Vandalises plants.

Prone to jumping if startled.

Very messy.

Overall:

Not for the beginner. Oscars are pigs and can be bastards.

AQUARIUM CONDITIONS

Minimum aquarium size: 120 cm X 40 cm.

Water temperature: 25 C.

Water salinity: Freshwater only.

Filtration & oxygenation: Oscars are pigs so particular attention need to be payed to water quality.

Lighting: Not critical.

Plants: I recommend heavy planting to subdue the lighting by day. Plants are also good for water quality.

Furnishings: Not critical, tank furnishings tend to be vandalised so must be robust.

Notes: Heater needs to be armored and filter should be solid due to this fish's vandalistic nature.

AQUARIUM BEHAVIOR

Oscars are renowned for their character and intelligence. They have large, well developed brains which they seem to use to dream up new ways of rearranging their aquarium. My Oscars were quite well behaved when they were young (3 to 6 cm) however when they reached their adolescent years they started to run amok. They had to be isolated to their own tank to avoid the killing of any of my other fish. They even went so far as to attack fingers which often drew blood. Now that they are mature they are more mellow and tolerate other fish (just as long as they know their place). Slayer and Duke like to rearrange their aquarium furnishings. I tried to stop them from moving a plastic plant by siliconing it to a large glass plate and burying it in the substrate. They somehow managed to drag the plate through the substrate into the corner of the aquarium, destroying most of the plant in the process. They even managed to move a 2 kg piece of slate from one end of the tank to the other. Oscars dislike aquarium equipment and have a tendency to attack it. They smashed one of my thermometers and attempted to destroy the aquarium heater which I had to bury in the substrate. Oscars seem to recognise individual people who move near their tank. They react differently to different people. Some people (like my mother in law) they hate, and will splash water onto them from the tank, or try to bite them. Other people they love and allow to pat them. I'll never listen to someone tell me that a fish has a memory of three seconds again. Oscars are very extroverted and rarely hide.

FEEDING HABITS

Oscars will eat almost anything. I feed mine on live fish, frozen fish, beef heart, and cichlid pellets. They have large mouths and small throats so when they eat they make a terrible mess with uneaten food particles left all over the place. This means that their tank needs to be cleaned often. I recently solved this problem by introducing a sooty grunter to the tank. It ate all the scraps. Unfortunately it died from being overfed.

FISH KEEPING RECOMMENDATIONS

Oscars are large and aggressive. They need a big tank. Oscars do well in pair or by themselves but can be kept with other suitable large and aggressive fishes if you know how to do it. They are pigs and put a large demand on the filtration system so you need a good one. Oscars are aquascapers (they move everything around) and if they don't like an item they will attempt to remove it. This includes heaters which must be guarded. Do not put any breakable equipment or plants in their tank. Otherwise they are an easy fish to maintain in captivity.

'Slayer' is large and aggressive. Many people fear this particular fish. He has drawn blood from more than one hand. Even Elisabeth will not place her hand into his tank. Fortunately he only hates people, he doesn't seem to bother his tank-mates too much.

OUR FISH

SPECIMEN DETAILS

I keep two 28 cm fish of the original strain named 'Slayer' and 'Duke'.

AQUARIUM DETAILS

They live in a 270 cm X 60 cm tank, maintained at 24C. Filtered by internal power filters. No plants but illuminated. Has a coarse gravel substrate with several large rocks placed to provide hiding places. Also inhabited by large native fish.

The wart on Slayer's lip is a callous to protect his mouth when he brawls with other fish.

Minimum aquarium size:	120 cm X 40 cm.
Water temperature:	25 C.
Water salinity:	Freshwater only.
Filtration & oxygenation:	Oscars are pigs so particular attention need to be payed to water quality.
Lighting:	Not critical.
Plants:	I recommend heavy planting to subdue the lighting by day. Plants are also good for water quality.
Furnishings:	Not critical, tank furnishings tend to be vandalised so must be robust.
Notes:	Heater needs to be armored and filter should be solid due to this fish's vandalistic nature.