“We say again, we desire to give nothing on our sole authority. Therefore we cite Jacolliot, who, however criticized and contradicted on other points, and however loose he may be in the matter of chronology, (though even in this he is nearer right than those scientists who would have all Hindu books written since the Council of Nicea), at least cannot be denied the reputation of a good Sanscrit scholar. And he says, while analyzing the word Oan, or Oannes, that O in Sanscrit is an interjection expressing an invocation, as O, Swayambhuva! O, God! etcetera; and An is a radical, signifying in Sanscrit a spirit, a being; and we presume, what the Greeks meant by the word Daemon, a semi-god.
“What an extraordinary antiquity”, he remarks, “this fable of Vishnu, disguised as a fish, gives to the sacred books of the Hindus; especially in presence of the fact that the Vedas and Manu reckon more than twenty-five thousand years of existence, as proved by the most serious as the most authentic documents. Few peoples, says the learned Halled, have their annals more authentic or serious than the Hindus.”
We may, perhaps, throw additional light upon the puzzling question of the fish-symbol by reminding the reader that according to Genesis the first created of living beings, the first type of animal life, was the fish. “And the Elohim said: ‘Let the waters bring forth abundantly the moving creature that hath life’…and God created great whales…and the morning and the evening were the fifth day.”
Jonah is swallowed by a big fish and is cast out again three days later. This the Christians regard as a premonition of the three days sepulture of Jesus which preceded his resurrection – though the statement of the three days is as fanciful as much of the rest, and adopted to fit the well-known threat to destroy the temple and rebuild it again in three days. Between his burial and alleged resurrection there intervened but one day – the Jewish Sabbath – as he was buried on Friday evening and rose to life at dawn on Sunday. However, whatever other circumstances may be regarded as a prophecy, the story of Jonah cannot be made to answer the purpose.
“Big Fish” is Cetus, the latinized form of Keto – khtw and keto is Dagon, Poseidon, the female gender of it being Keton Atar-gatis – the Syrian goddess, and Venus, of Askalon. The figure or bust of Der-Keto or Astarte was generally represented on the prow of the ships. Jonah, (the Greek Iona, or dove sacred to Venus), fled to Jaffa, where the god Dagon, the man-fish, was worshipped, and dared not to go to Nineveh, where the dove was revered. Hence, some commentators believe that when Jonah was thrown overboard and was swallowed by a fish, we must understand that he was picked up by one of these vessels, on the prow of which was the figure of Keto.
But the kabalists have another legend, to this effect: They say that Jonah was a runaway priest from the temple of the goddess where the dove was worshipped, and desired to abolish idolatry and institute monotheistic worship. That caught near Jaffa, he was held prisoner by the devotees of Dagon in one of the prison cells of the temple, and that it is the strange form of the cell, which gave rise to the allegory.”
H. P. Blavatsky
The Mark Of God: Understanding Your "I AM Presence" 