If there is another face-up Fish, Sea Serpent, or Aqua-Type monster on the field: You can Tribute this card to target 1 Spell/Trap Card on the field; destroy that target.
First of all, I'm really liking this card. Second, I hope it's a rare because it would be sad to have it as a secret rare (especially since I want 3).
This card is quite amazing when combined with Treeborn Frog or Deepsea Diva, for example, since you already meet the card's activation cost. It's requirement makes sure it's a candidate for BaniFish decks, since it can be removed and recycled if you want. Not just that, it's also quite searchable. It might not be revolutionary, but it certainly is a cool card.
Also notice how it says any Fish, Sea-Serpent, or Aqua type ON THE FIELD...that's right, it's even better when your opponent helps you meet the conditions.
And yes, tributing itself isn't exactly the best way to spend a summon, but it's requirement makes sure you don't stay defenseless.
Overall, this is a great card and I'm looking forward to playing it in either my BaniFish Deck (hopefully I will obtain it soon) or it might find some room in my old Codarus Control deck (Codarus+LBB=Eliminate 3 cards!). I dunno, worth a shot.