Additional rules

Nick Floyd, the designer of this format, also thought of additional rules:

Find Dory: Dandâns are considered every card type, allowing them to be retrieved with Mystic Retrieval or Mystical Tutor (and phased out with Vision Charm). 

Fish Eyes: Any card placed on top of the library that both players are aware of (i.e. a spell countered with Memory Lapse or a Dandân that is Metamorphosed) is placed on the library face up. 

In The Mind’s Island: Instead of using the free mulligan rule above, the players can remove four islands from the deck before dealing opening hands. Each player begins with two untapped islands in play, and play begins with the first player’s first main phase. Each player begins play with an opening hand of seven cards as normal and the standard Magic mulligan rules are in effect. This has the effect of a quick start and also forgoes the chance that only non-basic lands are played, preventing Dandâns from attacking a player. 

Remember the Fish: If the deck runs out of cards, and a player is forced to draw a card, he reshuffles the graveyard into the library before drawing a card. Players cannot lose the game by being forced to draw a card from an empty library unless there are no cards in the library or graveyard.

Thanks for the Fish: A card that refers to the “owner” of a card, is treated as referring to that card’s “controller” instead. This allows Ray of Command, combined with Unsubstantiate or Supplant Form, to steal a Dandân on a permanent basis.

Two-Headed Fish: Play with four players in teams of two, using the standard Two-Headed Giant rules, except each team starts with 20 life instead of 30 (to reduce the game time). During a team’s draw step, they determine which teammate will draw first.