The triggered ability can trigger only once each turn. It doesn't matter if Mystic Skyfish was on the battlefield when the first card was drawn. If it's not on the battlefield when the second card is drawn, the ability can't trigger at all that turn. It won't trigger when the third or fourth card is drawn.
23-06-2020
wotc
If a spell or ability causes you to put a card into your hand without specifically using the word "draw," it's not a card drawn.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.