Can Oscar Live With Gray bichir?

At full size neither can swallow the other, which is the first question to settle with two predators. The oscar's own profile rules out much smaller tankmates rather than comparable ones, and the bichir is a nocturnal hunter with poor eyesight that takes anything fitting in its mouth, so this depends on both fish being grown and evenly matched when they meet.

The shared range is 25 to 28 °C with pH 6 to 7.5.

Feeding is where it goes wrong in practice. An oscar is a fast, greedy daytime feeder while the bichir hunts by smell after dark, so food dropped at the usual hour never reaches the bottom; feed the bichir separately once the lights are out, with sinking meaty food placed near where it rests. The tank needs floor space rather than height, a long base with caves and wood, and the oscar's own 540 litre minimum is the figure to plan around. The bichir also breathes air and will drown if it cannot reach the surface, so keep the route up clear and the lid tight, since they climb out.