What fish do you think is the most disease resistant?

[Aquattro]

Clowns. I figure stress causes illness, and clowns are too dumb to get stressed over anything. I've also never had any issues with Yellow Tangs. My last one was with me about 10 yrs, my current one has been with me since day 3 of my tank running, never a problem with her.

[Carmen]

My wrasses have been VERY hardy! Easy going fish too with tonnes of colors to choose from!

[alfredshouse]

These are all great ideas, I appreciate it and keep em coming!!

[mike31154]

My current set up has been running something over two years and I haven't lost a fish to disease. There have been losses due to other reasons.

Here's the lineup (loosely in order of when they were added):

Maroon Clown & Blue Devil Damsel
Mandarin Dragonet
Copperband Butterflyfish (died of starvation)
Lawnmower Blenny (1. sucked into powerhead, newb mistake, 2. Jumper, 3. still with me)
Maroon Clown #2 (went through the difficult pairing process, now I have a spawning pair)
Yellow Tang
Singapore Angelfish
Blue Green Chromis x 3 (all gone, predation & bullying mostly)
Mandarin Dragonet #2 (recently added, thought it was female but is male, need to monitor since I now have two males, so far so good, huge size difference)

Last week I turned my ATO on manually to top up the tank, forgot about it, went shopping for a couple of hours. Came home & the tank was just starting to overflow with close to 4 gallons having been added to the system! Drained a bunch of water and checked the salinity which of course had dropped a couple of points in the two or so hours. The livestock seemed to know something was awry and were kind of hiding. In any case, once I drained the tank to a safe level, things got back to normal with no apparent ill effects. I also quickly mixed up a half gallon of concentrated salt water and added it in. I think the tank is large enough to forgive my boo boo. I kept the water I drained and refilled my ATO bottle with it. Hopefully this will get the salinity back to the original level in the course of 4 to 5 days. I'm about half way there and everything is fine, so I guess you could say, all of the fish in there are reasonably hardy. Even the inverts are doing their thing as if nothing happened. Colour me lucky.