Are fish roe unicellular? Are roe (fish eggs, caviar, etc.) single cells? I have tried looking this up on google (sadly, to no avail), and I am guessing they might be multicellular (like bird eggs) or consist of one cell plus corona cells, or indeed unicellular.

Yes; the first division starts at around **45min** post fertilization in zebrafish. This picture is stuck in every zebrafish lab.

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