I wouldn't...clown triggers are mean. And it will quickly outgrow a 75. If you get one small enough to fit in a 75 for long, it probably won't live long. (For some strange reason, the mortality rate on juvenile clown triggers is astoundingly high. Once they're passed a certain length (I think 6"? I could be wrong on that though.) they're tough.
I think you meant a clownfish and a Niger Trigger? If you meant a clown trigger and a niger then sistrmary is correct. Niger triggers are very peaceful, about the only trigger that is. The Clown trigger would terrorize(kill) a Niger most likely. I'm pretty sure a clownfish and a Niger would get along fine.
That is true about the Niger, but mine stays away from me, he's a big wus. I wish I could say the same for the stupid Domino I have in there. I kinda wish the Niger would make him disappear
Ive had a niger for 6 months. He grew to 5 inches. I then added a 3 inch clown trigger. They Love each other.
This only worked because the niger was established and I added the AGRESSIVE FISH LAST!