A Generation Fish Deck relies on banishing Fish, Aqua and Sea Serpent-Type monsters to trigger effects and for cheap removal. First, when your Fish, Aqua, or Sea Serpent is banished, "Wingtortoise" Special Summons itself from either your hand or Graveyard, creating advantage and ensuring some protection. Combined with "Airorca", "Flyfang", and "Skystarray", you can easily get one or more "Wingtortoise" out each turn (Note that in a similar manner to "Green Baboon, Defender of the Forest", you can only Special Summon ONE "Wingtortoise" per banished Fish/Aqua/Sea-Serpent). "Airorca," "Flyfang," "Skystarray," and "Big Jaws," all banish themselves and fulfil this condition easily.
Since most of the monsters are Level 3, they can be used to Xyz Summon Rank 3 Xyz Monsters, such as "Leviair the Sea Dragon", which can Special Summon Level 4 or lower banished monsters, allowing you to re-use your own monster like "Friller Rabca" or any monsters banished by "Airorca," or "Number 17: Leviathan Dragon", which rapidly overpowers most other monsters. An alternative, though harder-to-Summon Xyz Monster beatstick is "Shark Caesar". You can also Xyz Summon "Totem Bird", which has a powerful ability to negate a Spell or Trap card by detaching 2 Xyz Materials attached to it, or "Black Ray Lancer" which can be used on the opposite end of the spectrum to negate monster effects, though both have Attribute specific Summoning requirements. The Sea-Serpent Type "Number 47: Nightmare Shark" can be used to attack directly with its effect, while the risky option of "Number 30: Acid Golem of Destruction" is also available.
Because of the Types involved, "Spined Gillman" is a good support card, boosting the ATK of "Wingtortoise" and "Flyfang" to decent levels. "Deep Sea Diva" can search "Gillman" as well as "Airorca" and "Skystarray" for support or a Synchro Summon, though its recent Limiting thus limits the use of Synchro Monsters unless one uses "Leviair" to use your opponent's Tuner monsters. With the release of "Shark Stickers" in Photon Shockwave, the Deck gained the ability to make multiple Rank 3 Xyz Monsters in a single turn and return multiple monsters (via "Leviair") for Xyz and Synchro Summons. "Fish Depth Charge" can be used to provide a destruction and draw engine, though neccessitating the use of a larger proportion of Fish-Type monsters. "Fish and Swaps" can be used to recycle cards that are permanently banished by the effect of "Airorca". "Airorca" can destroy any monster on the field by banishing one monster from your hand, then banishing itself until the next Standby Phase, preventing your opponent from destroying it in retaliation.
"Nimble Sunfish" is an excellent support card, sending a Fish-Type monster to the Graveyard when it is destroyed by battle, and then Special Summoning another copy of itself from the Deck. This serves several purposes: the below-mentioned weakening capabilities of sending "Needle Sunfish" and "Friller Rabca"; loading the Graveyard with specific monsters to return to the hand with "Salvage" (though only WATER monsters); or loading the Graveyard with the neccessary cost for "Splash Capture", which will not only banish two more monsters for various purposes, but allow a potentially game-changing theft of an opponent's Summoned Xyz monster.
The majority of Generation Fish is dependent on Xyz Summons to produce big monsters and gain advantage. Without them, this Deck is dismally low on ATK power (with the exception of "Big Jaws" and any boosts granted by "Aqua Jet"). "Nimble Sunfish" is an extremely useful card as it can solve this Deck's lack of power. When it is destroyed (by battle), you send a fish monster to the graveyard to bring out another Sunfish. You can send "Needle Sunfish" to the Graveyard to weaken an opponent's monster permanently, or send "Friller Rabca" to the Graveyard to stop an opponent's attack and temporarily weaken that monster. Genex Undine can do the same when it's Summoned as long as you have a Genex Controller in your Deck. This engine also opens up Synchro Monsters like Genex Ally Triarm and Hydro Genex, though it takes up several spaces in the Deck.
This Deck also takes time to set up, given the nature of its search card and the need to send "Wingtortoise" to the Graveyard, especially when using the "Genex" engine, relying heavily on Special Summons to avoid losing ground, and is vulnerable to effects that can permanently remove "Wingtortoise" from the Graveyard, such as "Macro Cosmos" or "Dimensional Fissure", though "Oh F!sh!," "Leviair" and "Fish and Swaps" can be used to recover it.
Cards like "Imperial Iron Wall" and "King Tiger Wanghu", if played early, can dismantle the Deck, as "Airorca" cannot pay the cost for their removal. "Imperial Iron Wall", however, is vulnerable to "Mystical Space Typhoon" and "Lost Blue Breaker", while "Big Jaws" has enough ATK to run over "Wanghu". "Chaos Hunter" is another threat, as it acts similar to a one-sided "Imperial Iron Wall". Plus it can Special Summon itself when another monster is Special Summoned, enabling it to block the Deck's banishment strategy as soon as it hits the field. It also has high ATK, which can allow it to run over almost all the key monsters in the Deck without much trouble.
This Deck works with "Dimensional Fissure", continuously banishing Fish, Sea Serpents, and Aqua-Type monsters for effects while using "Wingtortoise" for repeated Xyz Summons. Since "Wingtortoise" will not be banished if sent to the Graveyard as an Xyz Material, it can be repeatedly revived and used with "Shark Stickers" to bring out Rank 3 Xyz Monsters. This Deck is more effective at limiting your opponent's moves than the standard Generation Fish, but lacks consistency.
This Deck focuses on chipping away at your opponent's Life Points with direct attacks while still retaining the strategy of the original deck. The key cards of this deck are "Skystarray", "Drill Barnacle" and stall cards. "Drill Barnacle" can attack your opponent directly and each time it lands a hit, it gains 1000 ATK. Unless your opponent stops your attack or destroys your card, "Drill Barnacle" can easily gain 3000 ATK while "Swords of Revealing Light" is active. Next to that, you also use "Skystarray" who has an infinite loop of attacking your opponent directly and banishing itself only to return during your next Standby Phase so it can attack again.