i had an aro, a bichir, a rope, and a lima shovelnose with a wolf at one point and they all did fine for a long time, until she (the wolf) got a little bigger (about 6-7") and started looking at everybody else a little funny, so i moved her, oh yeah, i had a clown knife in there too. she finally ended up in a tank with the shovel nose.and did fine, they both grew at about the same rate so no problems.