Fisch: How to Catch the Grandpa Horseshoe Crab in Desolate Deep

The Grandpa Horseshoe Crab is a Secret-rarity creature in Fisch, and it lives in exactly one place. It came in with version 1.94.0, and unlike most Secrets, it barely fights back on the reel bar. The hard part is getting it to show up at all, which is why most players stop casting blindly and let crab cages do the work.

Quick answer: Go to Desolate Deep, drop Reinforced Crab Cages across the Brine Pool and Desolate Pocket, run high universal luck (Aurora Totem plus Golden Shrimp Bait), then harvest the cages after a few minutes.

Grandpa Horseshoe Crab location and catch data

Everything about this crab is tied to Desolate Deep. Nowhere else on the map produces it, so testing other deep-water zones only wastes time. Within Desolate Deep, the two spots that matter are the Brine Pool and the Desolate Pocket.

Detail	Value
Rarity	Secret (chance increases with luck)
Location	Desolate Deep
Rod spots	Desolate Pocket
Crab cage spots	Brine Pool, Desolate Pocket
Resilience	500 (Very Easy)
Preferred bait	Golden Shrimp Bait
Weather	Clear or Rain
Season	Spring
Time of day	No preference
XP	80,000
Value	3.16 C$/kg

Weight runs from 4.5kg at the low end to 20kg without external boosts, with a true average around 7kg. Anything above 9.5kg counts as Big, and 18.9kg and up registers as Giant.

Fastest method: Reinforced Crab Cages in Desolate Deep

Cages beat casting because they roll passively while you do something else. Volume is the whole trick here. A handful of cages will eventually produce a Secret, but a full spread of them compresses that wait into minutes.

Travel to Desolate Deep. Use the Traveler’s Whistle menu and pick Desolate Pocket under the Desolate Deep region so you land in the right pocket instead of sailing there manually.

Fisch hotbar with the Typhoon Poseidon Rod equipped while travelling toward Desolate Deep — Gear up before the trip so you are not swapping rods once you arrive. Image: Cleverlike Studios

Place an Aurora Totem near where you plan to set up. It raises your luck for the whole session, which directly improves Secret odds since this crab favors luck.

Equip Golden Shrimp Bait, or another high universal luck bait if you do not have it. Golden Shrimp is the crab’s listed preference, added in version 1.95.2.

The Deep: Abyssal Luminescence quest tracker on screen while swimming through the Desolate Deep water — The Deep: Abyssal Luminescence tracker stays visible while you set up in Desolate Deep. Image: Cleverlike Studios

Drop your crab cages along the water, going as high as 100 if you have them. Reinforced Crab Cages are the ones to use, since they hold up better than the basic version across a long farm.

Crab cages laid out across the Desolate Deep shoreline before harvesting — A dense spread of cages placed along the water in Desolate Deep. Image: Cleverlike Studios

Wait a few minutes, then harvest everything at once. You will get a long scrolling list of catches, and the Secret will be somewhere in that stack.

Catch feed scrolling after harvesting crab cages, ending on a Grandpa Horseshoe Crab — Harvesting the full cage spread produces a scrolling catch list. Image: Cleverlike Studios

Tip: set your cages first, then go fish or hunt while they fill. Standing next to them does nothing for the timer.

Spearing the roaming Grandpa Horseshoe Crab

This crab also appears as a roaming creature on the seafloor, and it shows up there fairly often. That makes the spear route the most direct one available, because you can see the target instead of waiting on a roll.

Dive into the Desolate Pocket and glide along the glowing terrain. Keep your camera low and scan the floor rather than the open water.

Equip a spear or harpoon gun once you spot one. A Royal Spear works fine, and a single clean hit is enough to secure it.

Strike the crab and check the XP popup. A roaming catch with buffs running can pay out heavily, well past what a normal Desolate Deep fish returns.

Rod fishing in the Desolate Pocket

A rod works too, but only in the Desolate Pocket. It is the slowest of the three approaches, so treat it as something you do between cage harvests rather than your main plan.

Bring a high-luck rod such as the Olympian Rod or Godbreaker, stack any luck potions and buffs you have, and cast with Golden Shrimp Bait on. When it hooks, the Secret exclamation pops above your head with the usual shimmer sound. The fight itself is trivial, since 500 resilience puts it in the Very Easy bracket and the bar barely moves.

Poseidon Rod selected in the hotbar while casting into the water in Fisch — Casting with a high-luck rod equipped in the Desolate Pocket. Image: Cleverlike Studios

How to confirm the catch registered

You will get a catch message naming the crab and its weight, for example a line reading that you caught a Grandpa Horseshoe Crab at 11.6kg. Your character also fires one of its catch quips, such as “That thing is old..” or “Oh a wise guy!”, which are unique to this creature.

The Bestiary is the other check. Because it is a Secret, the entry stays hidden until your first catch, then fills in with the Desolate Deep location card. If you are running The Deep: Abyssal Luminescence, the objective to catch one with crab cages ticks over to 1/1 the moment a cage produces it.

Common reasons the crab does not appear

Problem	What to change
Farming outside Desolate Deep	It spawns nowhere else. Return to the Brine Pool or Desolate Pocket.
Wrong season or weather	Spring with Clear or Rain is the strongest window. Time of day is irrelevant.
Rod casts in the Brine Pool	Rod catches only work in the Desolate Pocket. Use cages in the Brine Pool.
No luck stacking	This Secret favors luck. Run the Aurora Totem, luck potions, and a high-luck rod.
Too few cages	Small placements roll rarely. Scale up toward 100 Reinforced Crab Cages.
Confusing it with the boat	The Grandpa Horseshoe Crab boat came from the HarpoonGunsNextWeek code, not from catching this creature.

Note: do not mix this up with the plain Horseshoe Crab, which is the Common version pulled from the same crab cages in Desolate Deep. Seeing a pile of those in your harvest list is normal and is not a sign your setup is wrong.

If you are chasing the Bestiary fill rather than the sell price, cages plus a roaming sweep is the efficient loop. The crab is worth very little per kilogram, but at 80,000 XP a catch, a Spring farm in Desolate Deep pays off in progression rather than C$.