The mooris are more likely to pick on the front if its just 1, if you have 1 male thats 4.5 you can add the smaller ones, because the fronts will all stay together on 1 side of the tank, and the alpha will put the moori in their place. Fronts and mooris don't grow as slow as people believe, the slow growth is more because it takes them 2-3 yrs for males to become sexually mature, but they will easily hit 5-6" in the first year, and then slow down a lot. I keep mooris with my Mpimbwes, and have had no problems. I would say go for it, but keep an eye out for aggression, and to also feed the fish on seperate sides of the tank, because the moori are much faster and active and will steal all the food if you don't. If you absolutely want to make sure, then wait until you get the 125 and add the fronts in there first and then add the dolphins, IMO there should be no problem in the 125.