I had a great spiny boxfish for about 2 months before he actually got stuck face first in the outlet part of my filter where the water is returned to the tank from the sump. He was about 3-4 inches, very curious and friendly, always a big appetite for live or frozen brine shrimp. He probably was curious where all that water came from and swam straight into it until he became stuck, which is how I found him one morning :-( I absolutely recommend this fish, he used to let my cleaner shrimp ride around on him while he'd swim back and forth. I've heard that larger boxfish can be hard to get to feed and just waste away but I had great success with my little guy who was very healthy and happy until that one day..... By the way, I plan on getting another just like him but I will first make some sort of cage around the water outlet.