And here is the Sea Serpent-flavored White Fish deck I promised you. I replaced most of the ice themes with deeper waters (Ran Aegirine is still a free Gymir). Honestly, this is probably the weaker and less consistent version of the two, but I love and am equally committed to all of these engines. I even sided a tiny Mermail package. I didn't want the deck to go over 40 since you want to see Diva more than anything, but maybe you could take out one Heavy Infantry and something else. The idea on that is to add Abyssteus to hand with Abyssalacia so you don't have to waste Abyssdine's summon on your opponent's turn. But I digress.
Summoning Guitar Gurnards Duonigis, hands-down the coolest Sea Serpent, with Diva gets you level 7 or 8 synchros. With all your free summons, it just snowballs from there. Atlanteans do Atlantean things to hand-loop; DS Minstrel is an anti-handtrap; and the other Deep Seas are extenders when discarded/ss'd. Chengying might be a better pick than Bihamut, who just starts with higher attack. I wanted a big beatstick to contend with "unaffected" monsters. Duonigis does give an attack buff from the gy.
Sadly, we are only getting 1 Toad off of Bahamut Shark with this deck. The only level 2 Aqua that would fit with this deck is Swap Frog, and trying to field 2 of him is just too hard. Plus I don't wanna pay his tax when I could still run Ran instead. Boy I'm looking forward to these water cards. I hope they're not expensive.