he was living with a royal pleco and a shoal of 12 clown loaches. i took them all out though because for some reason one day the loaches just stopped coming out of their driftwood stump...... for a few weeks. was it cause my jar "snapped" i dont know for sure so i cant tell you a definite answer. however for the most part he would only check them out when they went to the top of the tank but thats probably because thats his territory to begin with. He prolly didnt attack them either because i had all the loaches with him since he was about 6'' or so and i never fed him feeders. As far as realistic size ive seen a few videos of 24'' jardinis on youtube but they were all 4+ years old. biggest one ive seen in person was about 20" but it was starting to get the girth you see in older jars. if your looking to get one i would just expect to have him alone in a tank unless you have a massive tank because ive heard some pretty bad horror stories of jars going psycho and mutilating all its tankmates.