Clown loach wil rid you of snails very quickly but they also grow to 6-8 inches. I bought a baby and my snails were gone in two days I still have him and he's about 5 inches and happy in a 125. If I need a snail clean out of any of my tanks I just add him for a day or two then move him back
Clown loaches get WAY too big for 55 gallon tanks. I also recommend assassin snails. I have two in my 55 gallon and they cleared it of snails in a couple months (pond snails and ramshorns).
yoyo or zebra loaches could fit into a 55g. I would only get them if you plan to keep them. you would need at least 4. if you didnt want to add snails to get rid of snails. kinda seems pointlessly funny but the assassin snails do look cooler and can be removed when done.