Overall, I think the salvini is a difficult fish to stock around. The only success I have had with mixing them(other than temporarily) with others was with an oscar that was 3x the size of the male salvini. The oscar could not catch the salvini and gave up trying and his size kept the salvini in its place for the most part. I removed the salvini at about 6" because it was a fin nipping hit and run type of fish. For a long term situation I can see a lot of potential issues with just about any fish I can think of, especially if dealing with a pair. I think when mixing them with other fish it is probably best to keep a single salvini. This is the male I had.