If you prefer the jag over the red devil, then I'd be concerned. If you prefer the rd, you're good to go. Jags are nasty with some impressive teeth, but a male rd hits like Mike Tyson, especially when you're pushing 15-16" and beyond.
Alright thanks, and i just got him back last night and put him in the 125, he seems pretty peaceful and my friend had him with a convict and parrot and it was getting bullied. So hoping its a female or a nice male lol
Some click earlier, but usually around 10" there is an attitude problem. I think your best bet might be if they are both male. Then they would just fight for territory, and not breeding dominance, which is a nastier fight. I'm not sure about jags, but most amphilophus species can be expected to fight viciously for a territory somewhere around 4 feet, which can be a problem if they claim a bit of rock work in the center of the tank. You may have luck keeping clearly defined territories on opposite ends of the tank and leaving a no mans land in the middle.
I have rocks everywhere , a big fake stump, and lots of plants. So far the devils been in stump and jags been by rocks, and I have an oscar that is just there lol if it works with him ill keep him in but as soon as I see him getting fins nipped he's moving to another tank
Oh man lol well so far he's the most peaceful one in te tank, and te jag gill flares and stuff but the devil just ignored him. So hopefully they'll be okay