Why was the Hebrew word for 'fish' in Jonah 1:17 different from the one in the next verse?

Jona 1:

17 The LORD appointed a great fish to swallow up Jonah. And Jonah was in the belly of the fish three days and three nights.

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Strong's Hebrew: 1709. דָּאג (dag) — 19 Occurrences

LXX used G2486 (ἰχθύς, ichthys).

The very next verse, Jon 2:

1 Then Jonah prayed to the LORD his God from the belly of the fish,

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Strong's Hebrew: 1710. דָּגָה (dagah) — 15 Occurrences

Again, LXX used G2486.

The shift from masculine dag (Jonah 1:17) to feminine dagah (Jonah 2:1) served a literary purpose. It was a linguistic change in gender, not in biological sex. A big (masculine) fish swallowed Jonah. From the belly of the (feminine) fish, Jonah prayed to God. The semantics were the same; it was a stylistic variation. There was no theological difference. In LXX, they were the same Greek lemma G2486. In both verses, the word for 'belly' was masculine.

Jonah proceeded to pronounce his poem in 2:

2 “I called out to the Lord, out of my distress,
and he answered me;
out of the belly of Sheol I cried,
and you heard my voice.

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Wiki:

In the book of Jonah chapter 1 verse 17, the Hebrew bible refers to the fish as dag gadol, "great fish", in the masculine. However, in chapter 2 verse 1, the word which refers to fish is written as dagah, meaning female fish. The verses therefore read: "And the lord provided a great fish (dag gadol, דָּג גּדוֹל, masculine) for Jonah, and it swallowed him, and Jonah sat in the belly of the fish (still male) for three days and nights; then, from the belly of the (dagah, דָּגָה, female) fish, Jonah began to pray."[14]

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The shift from דָּג (dag) to דָּגָה (dagah) served as a deliberate stylistic choice in the narrative. In biblical Hebrew, nouns had grammatical gender (masculine or feminine), but this did not imply a real-world distinction in sex or biology. Instead, the alternation between masculine and feminine words enhanced the literary quality of the text by emphasizing different aspects of the same entity.