I have a Pearsei in my 210g with a mix of many smaller fishes and he is very mild tempered. He will give a little chase to some large red hook silver dollars but only at feeding time. Bocourti might be another one to consider, a tad more aggressive than a Pearsei but still in the gentle giant category. I am in the process of growing out some Paraneetroplus heterospilus that I got from Rapps, these have a rep for being pretty mild. They dont get as big as a Pearsei but my friend has one that is easily a foot but most of the times I think its said 10".