What can I put in a 55 gallon saltwater fish tank? Also equipment?

no on the tang wayy too small of a tank to make him happy, no on the eel he will foul the water too much for you to keep successful corals, get a bigger heater, and more lighting i have 48 watts on my 14 gallon and want more, your going to need a protein skimmer for sure go with a reef octopus