Check with your airline. If they are unhelpful, check with another airline.

Exceptions to the liquids rule are legion. (It would be faulty logic to conclude "because the rule is so stupid" but...) Live fish are regularly shipped as cargo in specially-designed containers—exotic tropicals sold in North Dakota pet stores probably were not bred there!

Plus, your daughter's particular fish are personal pets now, not commercial goods, so may fit into some special category which allows them in the cabin. Check show dog/cat enthusiast websites for recommendations about which airlines are the most pet-friendly.

There's gotta be a way; she certainly can't drive them that far. Good luck!