There you go. See I told you that it does not say "as big as a cedar". Do you know how a cedar moves? I can move my finger like a cedar even though it is nowhere near as big. A hippos tail, if you slow it down, moves very similar to the way that a cedar moves.
Once again, who understood the Bible better, here is a hint, it was not you. "moves like a cedar" does not mean "as big as a cedar". You were listening to Liars For Jesus again, weren't you.
He moveth his tail like a cedar not like a wisp or swallow tale.
And of course you did not look up the rest of the description.
Job 40:15-24
15 Behold now behemoth, which I made with thee; he eateth grass as an ox.
16 Lo now, his strength is in his loins, and his force is in the navel of his belly.
17 He moveth his tail like a cedar: the sinews of his stones are wrapped together.
18 His bones are as strong pieces of brass; his bones are like bars of iron.
19 He is the chief of the ways of God: he that made him can make his sword to approach unto him.
20 Surely the mountains bring him forth food, where all the beasts of the field play.
21 He lieth under the shady trees, in the covert of the reed, and fens.
22 The shady trees cover him with their shadow; the willows of the brook compass him about.
23 Behold, he drinketh up a river, and hasteth not: he trusteth that he can draw up Jordan into his mouth.
24 He taketh it with his eyes: his nose pierceth through snares.