I think your all forgetting about groupers. If not the same as groupers are eels. Probably the hardiest of all including damsels. Want color? Miniatus, Polleni, Louti, Argus, etc. All are super colorful, though you may not see them all the time You can cycle a tank easily with most groupers. What angels, tangs, gobies, or puffer can you cycle a tank with? When I worked at LFS more than a decade ago we had a 12" panther grouper that was given on loan to cycle large FO tanks. This Panther did the job time and time again with the most novice of fish keeper. This was befor LR was used commonly. Some Lions and triggers are almost as hardy. Regards, Tim