Ditto above poster, You have plenty of options in a 55g but I would start by researching what kinds you like. Also how you plan to set the tank up, live plants, fake, lots of rocks.....and filtration.....
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"There he goes - one of God's own prototypes -
a high powered mutant of some kind never even considered for mass production.
Too weird to live, and too rare to die".
Fear and Loathing in Las Vegas