mine was hardy, The water quality was never spectacular at the time because they are such messy eaters and doing changes on a 220 is a pain..
I tried to put a miniatus grouper in with the blue spot but the blue spot was super agressive immediately and I had to return the mini.
The best tank mates I had no problems with was a 24 inch zebra moray and a decent sized volitan. But the volitan really had some trouble at feeding time because the grouper is relentless. I could give him an entire soft crab and 6 jumbo shrimp in one meal.. I worked for a seafood place at the time, thats the only way i could afford to feed him, he ate better than me.
And they like to splash water on the floor. Interesting thing about the blue spot was he could change color. WHen he was content he was a beautiful powder blue color, when he was mad he was jet black with white dots and blended with rock perfectly. Great personalities though like triggers