It's hard to say if the fish you mentioned (Oscar, Jag, Midas, etc) will get along with other fish, but the chances of them not getting along are gonna be far greater than the chances of them getting along. I use to have a jag and he was hyper-aggressive. Anything that came near his tank, even me walking up to it, would get him flared up and attacking the glass. I currently have an 11" oscar that is very aggressive and O can\t put anything in with him or he would kill it. The previous owner of him got rid of him because of that reason when I picked him up last year.
One thing with clown loaches is that they have switchblade like barbs that will pop out and get the fish lodged in the throat of a fish that tries to eat them, so that's something to keep in mind.
Growing up fish together from very small can help a bit, but even then it's still pretty dicey with the species you are talking about unless you have a really REALLY big tank.
One thing with clown loaches is that they have switchblade like barbs that will pop out and get the fish lodged in the throat of a fish that tries to eat them, so that's something to keep in mind.
Growing up fish together from very small can help a bit, but even then it's still pretty dicey with the species you are talking about unless you have a really REALLY big tank.