Fluffies appear in multiple different sizes in this game, unlike the online version. Small ones are worth 1 coin, regular sized ones are worth 2 coins, and large ones are worth 4 coins. You must use a small Fluffy as bait in order to catch a large one. If you catch many Fluffies, but no squids, the Mullet appears, and can be hooked with a Fluffy on your line, of any size. Like in regular Ice Fishing, you get a large bonus for catching Mullet.
Squids are unique to this version of Ice Fishing, and are worth 4 coins each. Unlike Fluffies, squids move much slower. They also only appear later in the game. If you catch a lot of squids, a crab will walk across the bottom of the screen with a treasure chest. Catch a squid and lower it down to the chest and the squid will grab it.