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.
In Elite Penguin Force Mission Damage Control, you need to help Jet Pack Guy retrieve some blueprints that were dropped underwater (in a treasure chest) by playing Ice Fishing.
If you catch the Mullet or a treasure chest, in the final cutscene, your penguin appears blue, no matter what color your penguin is.