Generally most gobies are disease resistent due to their slime coat.
He killed a trimma goby, two Griessingeri gobies{<<<expensive little guys!}, and I forgot, a tailspot blenny. These were not all at the same time, but they were in a 12 gal nano. The goby was probably protecting his turf. But, I also have two yellow watchman gobies in my 90 that will swallow small fish. I have seen a pic of a yellow watchman with a firefish sticking out of his mouth. Large mouth shrimp gobies do have the potential to eat small fish and inverts. Not all fish are the same though, that is true.
Are you going to perform hyposalinity and leave the tank fallow{no fish} for 6 weeks? The ich can be in the tank and when you put the fish back he can get ich again. Cryptocaryon irritans{ich} has a life cycle, it will appear as trophonts{spots] on the fish, burrow into it's skin, then drop off to the substrate and rock. Lay it's eggs, and the cycle starts over. Many people have ich in their tanks and do not even know. It goes unnoticed as it jumps on and off the fish. Ich does not want to kill it's host, on the contrary..it needs it. But when a fish gets stressed for whatever reason it loses it's slime coat. This is when the ich attacks with a vengeance, clogging the gills and ultimately killing the fish if steps are not taken quickly.
