Mellow amphilopus?

[Randys]

Ya, I know, this is an oxymoron, but there any species less aggressive than the rest?

 

[Rocksor]

A. lyonsi tends to be less aggressive

 

[duanes]

I have not found any Amphilophous to be overly aggressive, but its all about proper tank size.
If the fish sees the tank as too small, it will be aggressive, if there is enough room for the stock population, of the tank, it won't be aggressive, unless its spawning. Its not what we (humans) believe that counts.

 

[Gourami Swami]

I did find A. Lyonsi to be less aggressive than some of the others I have kept like hogaboomorum or chancho; but I wouldn't call them mellow as a species exactly. It's more about the individual fish, I have seen plenty of midas etc that worked with other fish, and I have seen lyonsi which needed to be solo as well. I think tank size will play a large part in the equation like duanes is saying.