Need some suggestions

[Sturgeon]

I have a 125 tank that I will be putting my fish in within the week. I have a Black Volitan Lionfish and a Porcupine Puffer. I would like to get another fish that the puffer could swim around with.(I heard they like other fish to "play" with) I need some suggestions on what type of fish I could put in there and 1. not get eaten 2. fit in there with the other two fish. I am upgrading from a 55 gal. but I don't want to go bigger than the 125. I would like a fish that is active, unlike the lionfish.