I have a 55 gal. tank thats been up and running for 4 years, 18 months ago I took it down from my sisters hous and moved it to my house. I took 90% of the water with me, a damsel fish a handful of crabs and 120lbs of live rock. I moved it all in large new coolers and set it all back up at my house. After letting the tank run for 4 months I put in 15 snails,12 hermit crabs and a cleaner shrimp. Two months later I put 3 fish in a marron clown, a yellow angel, and a dimond goby. In two days the goby was dead. The water check out with in normal limits. I didnt bring in any new fish for a year I did my water changes and the remaining fish were fine. Friday I put a Flame angel and a watchmen goby, today the goby was dead I took it back to the LFS along with a water sample. My water is fine I started talking about my goby issue and was told it was a substrate Im using the fine crushed coral he told me the goby was choking on it that it was to course. what do you guys think? Help please Im not going to get another one if its going to die.