Diamond goby
Lawnmower blenny
Flame hawk
Jawfish (if you have a deep sand bed, and some lr rubble for them)
6 Line wrasse
dont get damsels... EVER!!!
Nearly every lawnmower blenny I have tried to feed will go for some nori. I have a friend who has one eating all sorts of frozen food as well.Lawnmower wouldn't be a good choice either, most don't eat any food given, they live off the algae from the rocks. A 56gal won't have enought algae to keep them going.
Actually... to be blatantly honest with you. The best is to:
1) borrow a well fed (in hawaii we use freshly caught) large naso tang and put it in a 5 gallon bucket with an airstone and leave it there for 24 hours
2) return the naso to its owner and dump all of the bucket's water and crap from the naso into your bio-filteration and let that sit for a 3-4 week period..... then add fish.
Actually... to be blatantly honest with you. The best is to:
1) borrow a well fed (in hawaii we use freshly caught) large naso tang and put it in a 5 gallon bucket with an airstone and leave it there for 24 hours
2) return the naso to its owner and dump all of the bucket's water and crap from the naso into your bio-filteration and let that sit for a 3-4 week period..... then add fish.
Generally you need to experience ammonia spikes and all kinds of horrible "new tank tragedies" so just get some cheap cute fishes like clowns or even better--fish that are typically found in 1-10ft. depth of water in the wild. Tide pool fish are especially winners because they are used to extreme conditions [like long periods of hot water temps, high salinity levels, and low dissolved oxygen levels]. These are your best choices of starter fish. After 1 year then you graduate to your "real fishes".
Sorry, I don't think this is particularly good advice. There are better ways to cycle a tank and using "throw away" fish in the beginning is somewhat tacky.