You can only use the 1st effect of this card’s name once per turn.
(1) If all monsters you control are WATER monsters (min. 1), you can: You cannot Special Summon monsters for the rest of this turn, except WATER monsters, also the next battle damage your opponent takes this turn from a battle involving your “Number” monster and another monster is doubled, also Special Summon this card from your hand, and if you do, add 1 Level 3, 4, or 5 Fish monster from your Deck to your hand, except “Abyss Shark”.
(2) If this card is used for the Xyz Summon of a “Number” monster, it can be treated as a Level 3 or 4 monster.