even a 1500 gallon is too small for a leapord shark much less 2 much less getting 2 to breed. you should go to a publich aquarium and see how big they get before you try a shark tank
i have a clown trigger in my 150 gallon stock tank used as a rdsb, he gets as much attention as my 600 main tank for some reason, probably his outgoing personality :D
my porcupine puffer is fine with my damsels, foxface, tangs, harl tusk, soft corals, everything. only drawback, it is an absolute pig and will eat its own bodyweight if i let it.