Velvet cichlids or oscars (Astronotus ocellatus) are popular freshwater pet fish due to their hardiness, character and unique appearance. Most oscars in the pet trade are sold as one or two inch long juveniles. At this stage they are vastly different fish than when they grow to be over a foot long by the time they are full grown.
The most important aspect of an oscar tank is size. It should be at least 55 gallons large. A heater is also a must as this species is native to South America. Another must is a tight-fitting lid. Oscars are powerful fish and can easily leap from tanks to their deaths. Decorations or plants can only safely be added when the oscar is still a juvenile. Be sure to add at least one type of filtration as large fish excrete a lot of waste.
Oscar Juvenile Tanks
Aquariums for oscar juveniles can be the same as for a community freshwater tank. Oscar juveniles seem to realize that they are small enough to make a tasty meal for many predatory fish. Even if none of those fish are in the tank, the oscar juvenile will still want to instinctively hide from them.
Neal Proneck, author of “Oscars” (TFH Publications; 1993) recommends that many plastic plants, aquarium-safe rocks and other decorations should be placed generously in a tank with one or more young Oscars in order to provide hiding places to make them feel secure. Even a couple of bushy plastic plants can make an adequate bolt hole.
Once the juvenile approaches six inches long, it is likely to stay out in the open more and then will begin “redecorating” its tank by tossing the decorations about. It’s time to remove the decorations.
Gravel or Substrata
Both juveniles and adult oscars need gravel or aquarium sand in the bottom of the tank. A depth of one and one-half inch is adequate. Substrata helps to promote growth of healthy bacteria and gives the oscar something to do. Their usual method of feeding, in between large meals like earthworms or feeder goldfish, is by picking up a mouthful of gravel, swallowing edible material and spiting the gravel back out.
This is why live or plastic plants do not fare well in oscar tanks. Oscars will constantly rip the plants out of the gravel. OscarFishLover.com recommends adding heavy aquarium-safe pebbles on the bases of fake plants, but some Oscars will still manage to knock the pebbles over.
Large, flat aquarium safe rocks such as slate are excellent for an oscar tank, especially if the owner is trying to breed the fish. The female needs large flat rocks on which to deposit her eggs.
What About Floating Plants?
Oscars generally uproot anything in the substrata. Neal Proneck recommends using floating plants – even live floating plants – in an oscar tank because in his experience Oscars tend to ignore them. Unfortunately, some oscars have not read Proneck’s book because they will rip apart just about anything, including floating plants. It all depends on the temperament of the individual oscar.
One of the joys and challenges of caring for oscars is seeing their individual personalities emerge and adapting the tank to suit their preferences.
Sources:
“Oscars.” Neal Proneck. TFH Publications; 1993
FishLore.com. “Oscar Fish.” http://www.fishlore.com/Profiles-Oscar.htm
OscarFishLover.com. “Oscar Tank Set Up.” http://www.oscarfishlover.com/tank-setup
Author’s personal experience
