My thinking here comes from hearing some trigger keepers claim that getting them very small and raising them up yields slightly better results, in some cases postponing aggression a little longer. Also considering that these are generally accepted as the 2 (to my knowledge) most aggressive triggers in the hobby. I know of no one who keeps a titan or queen. So based on what I've heard from other keepers, these 2 are top tier PITAs. The thinking was maybe they're both such punks, they might actually coexist, at least while still young, under the concept of mutually assured destruction. They would in theory for this test be the only 2 fish in this tank. It would be possible, though not planned, to add a handful of chromis or damsels. Main goal is to get them sharing space without igniting world war 3. Curiosity is a dangerous thing...Looking back on this discussion, it was a fairly stupid question. It can work in huge tanks. Most people are better off never considering tankmates. I also would not leave an undulate alone with 1 triggerfish.