Soon as the Orino get's size it will turn into a territorial battle with your Armatus. If he's already flaring up now, imagine when he is over a foot.
Tell you what, I'll pick him up this weekend and will relieve you of the stress with the worries if they will get along....
BTW - As for the Bicuda try to take a picture. Hard to say without seeing Pix's.
On the reals. Reason why I got rid of my Armatus with my PBass was because of the accidental jabs with my Armatus. It was just a matter of time until an accidental bump that was made by the Armatus and hits the PBASS's eye.... Don't under estimate an Armatus.. they are territorial and will also take jabs.