This is mainly a small "fun" build revolved around the Fisherman's and the White Aura's with the main focus of building up the GY and searching the Deck to spam a bit and make Synchro plays. That being said, the Legendary Fisherman III is more like a "bank shot" and only comes out occasionally, its more often a Tatsunoko or Moray of Greed target when its around too early in the hand.
The build isn't 100% perfect. I'm pretty sure there are some better cards to employ than some of these. If anything, its meant to be a skeleton as you can add and remove cards as you please according to you and also give yourself ideas on how to make a Fisherman Water deck playable.
I am aware there is a better way to play Fisherman with cards such as the Combat Star cards, but meh, often has felt weird to me playing them like that and it not being a true Water deck like intended for the monster and being true to Mako Tsunami. But I also wouldn't mind hearing ideas for Legendary Fisherman and seeing what kind of deck you can build around it whether Water or not.
Main idea is simple enough regarding combos, one combo only requires you needing a Megalo and Deep Sea Diva in hand.
>NS Diva
>Activate Diva effect, SS Neptabyss
>Activate Neptabyss effect, send Dragoon to GY, add a 2nd Dragoon to hand
>Activate Dragoon effect in GY, add a 2nd Neptabyss to hand
>Activate Megalo, discard Nebtabyss and Dragoon, SS Megalo
>Activate both the 2nd Neptabyss's and 2nd Dragoon's effect, Neptabyss will SS a Dragoon from GY while the Dragoon you discarded with Megalo will add another Megalo to hand or something else if already have a Level 7 in hand.
>Link off Diva and Megalo for Needlefiber
>Activate Needlefiber effect, SS another Diva
>Synchro Summon Tatsunoko with 2nd Diva and Neptabyss
>Synchro Summon Bihamut with Tatsunoko and Level 7 in hand (Probably Megalo if you added him to hand earlier)
>Activate Bihamut effect, SS Token
>Link off Needlefiber, the Token, and Dragoon for a Apollousa (3 negates)
Then opponent's turn, SS another Token with Bihamut.