A hypothesis remains just that, without a way to verify or falsify. If not a single word of underlying plaintext is known, that’s hard. So I’ll assume one. On page 70v of the Voynich Manuscript (VMS), image 127 in the collection of the Yale University, we see two fish, a star and the word “otolal” (in Eva transliteration), otolal in Voynichese. My assumption is that stands for ‘pisces’, in Latin.
Or could it be encoded Hebrew instead of Latin? Let’s investigate that first. The singular word ‘fish’ in Hebrew is דג, dag. There are two different plurals. One is דָּגָה, dagá, which occurs in the Hebrew Bible. Images of the concordance by Isaac Nathan ben Kalonymus can be seen and downloaded from Google Books. On page 243 of the PDF, in the header, all to the left, we can see d-g-h, דגה. Then in the leftmost column, a little below halfway, again d-g-h, something I can’t read (I don’t know Hebrew; can only decipher the alphabet, very slowly), the word bereshit, בראשית, ‘In the beginning’, the first words of the book of Genesis, therefore also used as its name. Then we see three lines, until it goes on with the next book in which the word דגה is found, shemot, שמות, ‘Names’, or in Latin: Exodus.
Each of those three lines contains, right to left, a bit of quoted context, then two groups of Hebrew letters, used as numbers, indicating chapter and verse:
|כו||א||וירדו בדגת הים|
|כח||א||וירדו בדגת הים|
|ב||מ||דגי הים בידכם נתנו|
Bereshit, alef, kaf-waw, that means Genesis 1:26. For comparison of the context, see the site of the Mamre Institute, where it says, fully voweled: וְיִרְדּוּ בִדְגַת הַיָּם.
Then alef, kaf-Het, or Genesis 1:28, different verse, but same words of context.
Finally teth, beth, Genesis 9:2, context: דְּגֵי הַיָּם, בְּיֶדְכֶם נִתָּנוּ.
However, this plural form דגה, dagá, is not used for the sign of Pisces, which in Hebrew is מזל דגים, mazál dagím. This word דגים is not used in the Bible. So I think we’re on the wrong track here: if parts of the Voynich Manuscript were encoded using the Hebrew Bible, it was not this part, not page page 70v. So I return to assuming it was in Latin, ‘pisces’, using the Vulgate Bible.