Literally, "battle between mice and frogs," an anonymous Greek mock-epic that parodied Homer. (The Romans attributed it to Homer, but the Greeks knew it was written a few centuries later -- probably the 4th century BCE.) Batracho- is the frogs, -myo- is the mice, and -machia is the battle. A nearly modern translation is here.
I knew it was a bad idea to put the rodent display next to the amphibian tank -- now we've got a batrachomyomachia as their keepers fight for expansion space.