I would say 200g is minimum for a fully grown up Lima.
You may keep with any big fish that doesn't fit in the limas mouth but beware that the mouth might seem to me small but it will eat kinda big tankmates, you can be amazed how big fish it may eat :O but the lima aint as predatory as the tiger shovelnose so you will be good with most big fish, not eel species like bichir though.