Very sorry to hear.
Advanced ich looks a lot like velvet (Amyloodinium) in fact, many people confuse the two. A microscope is the sure way to tell them apart. However, with ich, you don't see rapid breathing and not eating until the end, where with velvet, that shows up early in the infection. With advanced ich, the spots run together and get smaller looking.
The fin damage is likely from a secondary to the protozoan parasite. Marine Betta and snowflake eels are resistant to ich, and the eel is partially resistant to velvet, so that accounts for why they are still hanging on. I can't explain the bella goby though.
Low dose H2O2 is still experimental and being looked at mostly at the hobbyist level. A lot of this is being fueled by a a few papers where protozoans were controlled using peroxide dips. However, the dose was much higher 25, 75 and 150 ppm, for a shorter period. Using it for Cryptocaryon, on a very low dose, static bath basis is over-extrapolated from those studies IMO. Percarbonates have also been studied (resulting, apparently, in the formulation of Polyp Lab Medic).
I think that peroxides have a role in disease management, as an adjunct to UV, pristine water, good diet, heavy filtration, etc. I don't think they will ever be shown to be effective in low dose reef applications for active disease cases (acute cases where fish loss either has occurred or is expected soon).
Jay
