The "Great Fish"

The Hebrew words used to describe the "great fish" in Yonah 2:1 is dag gadol (which does literally translate as great [large] fish)...the passage reads:

Vayeman Hashem dag gadol livlo'a et-Yonah vayehi Yonah bimei ha-dag sheloshah yamim usheloshah leilot. 

Hashem designated a large fish to swallow Yonah, and Yonah remained in the fish's innards for three days and three nights. 


And Hashem appointed -Those sixteen days that Yisrael was missing the manna, since they did not eat it for a complete forty years - G-d took this manna and sustained the fish so that Yonah would not be digested in its intestines, and Yonah, too, ate within it from this manna.

A huge fish -It was a male, and he stood there with room, so that he did not think to pray. The Holy One, blessed he He, hinted to the fish, and it spewed him out into the mouth of a female, which was full of embryos, and it was crowded there, and he prayed there, as it is said: (v2) "from the belly of the fish (hadagah)." [from Pirk'd’Rabbi Eliezer ch. 10, according to Yalkut Shimoni ` Midrash Yonah, second version, Otzar Medrashim p. 219]