According to Planetcatfish they're territorial and best kept alone. I've kept a Watermelon with a Dull Eye with no problems, but the Dull Eye was half the size of the L330 so that may have been the determining factor. The size difference might have made the L330 consider the Dull Eye Royal a non-threat due to his size and left him alone because of that. You can give it a go, but remember to always have a spare tank just in case so worse case scenario you have somewhere to put the one getting beat on till you rehome him/her.