Jonah 2:1
1 Jonah prayed to the Lord his God from the stomach of the fish 2 and said, “I called out to the Lord from my distress, and he answered me; from the belly of Sheol I cried out for help, and you heard my prayer. 3 You threw me into the deep waters, into the middle of the sea; the ocean current engulfed me; all the mighty waves you sent swept over me. 4 I thought I had been banished from your sight and that I would never again see your holy temple. 5 Water engulfed me up to my neck; the deep ocean surrounded me; seaweed was wrapped around my head.
LXX Jonah 2:2
1 And the men feared the Lord with great fear, and they sacrificed a sacrifice to the Lord and prayed. 2 And the Lord commanded a great sea monster to swallow Jonah, and Jonah was in the belly of the sea monster for three days and three nights. 2 And Jonah prayed to the Lord, his God, from the belly of the sea monster, 3 and said, “I cried out in my distress to the Lord, my God, and he heard me; from the belly of Hades came my outcry, and you heard my voice. 4 You threw me into the depth of the heart of the sea, and rivers surrounded me; all of your swells and your billows have passed over me.
Notes and References
"... Though Jonah refers to the creature as a גָדּ (fish) four times (1:17 [2x], 2:1, 2:10), the ancients were acutely aware of the term’s ambiguity ... In Jonah, the ambiguity of the גָדּ, coupled with its enormous size, naturally encouraged the ancients to identify it as a type of giant sea monster known as a ןיִנַּתּ “Tannîn.” Thus, the authors of the LXX rendered םיִ֑לֹדְגַּה םִ֖ניִנַּתַּה “the great sea monsters” in Genesis 1:21 similarly: τὰ κήτη τὰ μεγάλα. The term ןיִנַּתּ refers generally to a type of serpentine creature of which Leviathan is one kind. Thus, the word ןיִנַּתּ takes the definite article (Genesis 1:21, Isaiah 27:1, Jeremiah 14:6, 51:34, Ezekiel 29:3, Nehemiah 2:13), whereas ןָתָיְוִל never does. Nevertheless, traditions concerning Leviathan are not entirely consistent. Thus, some texts understand the creature as possessing multiple heads, others see it as having one. Sometimes it also is equated with a lion or a sea monster with lionlike features ..."
Noegel, Scott B. Jonah and Leviathan Inner-Biblical Allusions and the Problem with Dragons (pp. 236-260) Studies in Judaism and Christianity from Second Temple to Late Antiquity Brescia 37, 2, 2015