I took me forever to find out what an ornate bichir can and cant live with and mostly got mixed results. So this is what i have found out, they can be put in with many types of cichlids as long as they arnt over aggressive such as red devils, texas etc. They can be with jaguar cichlids and others alike but they have to be watched due to the fact that they tend to be over aggressive but they can live together. I read that you shouldnt keep them with plecos some can live together fine but people say not to, especially with common plecs. They say not to do this because the plecs will some times suck the scales it happens fast but they do it over a long period of time which removes the bichirs natural slime and can kill the bichir. I just got a 7" ornate bichir that is in a tank with 2 oscars one 8" and one 5 1/2" a jack dempsey about 8" also 2 plecos one common about a foot long one albino bristle nose about 4" and a striped raphael catfish about 4 maybe 5". They all get together just fine, the common pleco dosnt like to be around other fish so always scares them away and isolates it self. The small pleco dosnt care about anything that is going on around it really. mainly it really just comes down to your animals personalities, and if you are going to get oscars and keep them with your bichir make sure it is atleast 7" if the oscar is 5" or bigger. That or put a baby oscar maybe 2 almost 3" in with a bichir that is at its smallest around 4 almost 5" because oscars grow very fast and bichirs every once in a while can grow 1" a month but thats not all to common, they go in growth spurts. This way the oscar is less likely to become aggressive toward it as it matures. But do be careful bichirs will eat any fish small enough to fit in there mouth and they can swallow whole, but they may not do it right off the bat. There are also some cases of them trying to eat fish that are to big for them to actually eat, in this case they may actually kill the fish whether they eat it or not. They also tend not to mix well with other eel like species. Remember bichirs are not very aggressive fish, for the most part they will live and let live unless it can be eaten.