Growing up together would give them a much better chance of working. I introduced a 12" jag to my 10" oscar in my 240. They got along great for about a month, had some liplocking going on the past few days, but have seemed to settle down and are fine now. Just have a backup tank. I also raised some young jags. I noticed they were a lot more timid at 3-4" and took longer to become more active.