If you are going to introduce a Tinfoil Barb and a Jag in the same tank, your best bet is to make sure that the Tinfoil barb is a few inches larger than the Jag. The Tinfoil Barb will most likely try to school with your other Tinfoil so he should have no problems from the Jag. The only bad thing that I see is that you currently have an 80gal. and a 150gal. Since Tinfoils generally do better in schools you may need to get more than two to coexist happily with a Jag and a Oscar. That's going to be hard in those tanks. Jags are very territorial cichlids. The Jag and Oscar will get pretty large and so will each Tinfoil. But apparently you're doing something right if you have raised one Tinfoil Barb to over 6". I think you should consider smaller barbs that can school in greater numbers in minimal space.