Backpacks
Inventory capacity for your caught fish. Separate from Energy and separate from fishing power.
What a backpack does (and doesn't do)
Your backpack is the cap on how many fish you can be holding, uncaught-and-unsold, at once. It's purely a capacity item. Backpacks carry no Luck, no Legendary/Mythic chance, and no fishing-speed bonus. If you want to catch better fish, upgrade your rod; if you want to catch and hold MORE fish before you have to sell, upgrade your backpack.
Stacks, not slots
Capacity is measured in stacked units shared across every species, not a fixed number of individual fish slots. A single stack of 20 Bluegill costs the same 20 units as 20 fish spread across five different rare species. There's no limit on how many different species you can be carrying at once, only on the total count.
What happens when it's full
If your backpack is full and you keep fishing, the catch isn't lost. It's automatically sold on the spot for its normal coin value, and everything else about the catch (XP, quest progress, collection records) still applies normally. It's a nudge to go sell or upgrade, not a hard wall.
The Tiers
Novice Satchel. Free starting backpack, 28 units. Durable Rucksack. 800 gems, 65 units. Pro Technical Pack. 2,500 gems, 145 units. Master Bubble Pack. 6,000 gems, 290 units (the current endgame tier). Buy and switch between owned tiers any time from /shop → Backpacks, or with /backpack (alias .bp/.satchel) directly.