It should learn it as it gains level, but if it doesn't then go to a move tutor that takes heartscales and give him a heartscale and he shall teach floatzel ice fang.
Chat with our AI personalities
You can teach it through a TM OR hove that dude who lets ur Pokemon REMRMBER a move in Pastoria
If you have a Floatzel, teach it 2 of the Five: Ice Fang Water Gun Swift Brine Aqua Jet The best move I would say: Surf and Waterfall
Either use a TM or go to serebii.net. On the website, look up floatzel. Look at the list of info and details. It will show all the moves floatzel can use, and MANY other useful things. :)
On generation 4 and above, level it up to level 21. It doesn't get to learn ice fang below generation 4.
Floatzel does not learn ice punch. Floatzel does not learn any ice type attacks naturally and must learn ice type moves via TM.