- Submitted by Saluki
When setting up an oscar tank, a few things need to be kept in mind. First, Oscars love to redecorate. If it is small enough for the oscars to move, it probably will be moved at one point or another. This rules out anything that is remotely breakable, such as ceramic ornamentation. It also rules out most plants (real or fake), since they will be killed/destroyed over time by the oscars. Fake plants can be used, but don't get elaborate in their use because whatever concepts you have in decorating your tank, the Oscar will have his or her own, and anything you do will eventually be undone by the Oscar.
Another consideration is that oscars move around a lot and are fairly clumsy. This means that they bump into things a lot. That rules out anything with sharp edges and/or rough textures, such as lava rock. Oscars have a habit of scratching themselves up or even ripping out large chunks of flesh, either of which, for a fish, can become life threatening.
Finally, remember that Oscars are softwater fish. Unless your water is extremely soft, you will want to avoid anything that will tend to raise the pH of the water in the tank. This rules out any calcium carbonate-based minerals such as coral, aragonite, limestone, marble, sea sand, and sea shells.
So, what does that leave us? A mainstay of oscar tanks is driftwood. The tanins in the driftwood tend to buffer the water to the lower pH range that Oscars prefer. Also, driftwood sold at retail normally is attached to heavy pieces of slate, so it is difficult for the Oscars to move it. Finally, plecos, which are a common bottom feeder in an oscar tank, like to scrape on driftwood.
Another good decoration is large river rocks. They tend to be smooth, so the oscars are not likely to injure themselves if they bump into a rock. They also give the tank more of a natural look.
Finally, every fishtank with egg-laying cichlids should have at least one piece of slate. This gives the fish a flat surface on which to spawn. If they do not have a convienient flat surface for this purpose, you will often find that they have dug spots in the gravel all the way to the glass.
Plastic/Silk plants can be used, preferably those with a weighted base, provided you don't mind your fish placing them somewhere other than were you intended. Your Oscar will toss these around almost like playtoys. Without a weighted base, most plastic plants in an Oscar tank will spend their time floating at the water surface.