Key takeaways
- Lighting order does not matter, but all three must be lit in the same visit. Leaving to rest and returning resets the lanterns.
- The spawn only registers if you are standing on the submerged stairwell when the clock passes 21:00. Waiting on the middle ledge does not trigger it.
How to Find Tidevex in Catch a Monster: Exact Spawn Map, Times and Catch Requirements
Tidevex spawns in the flooded lower chamber of the Old Cistern, and only during the night cycle after you have lit all three brine lanterns on the walkway above it. If you dive before the lanterns are lit, the chamber is empty no matter how long you wait. This guide gives the exact coordinates, the spawn window, the bait and rod requirements, and the step-by-step route from the Cistern entrance so you stop arriving late or fishing the wrong pool.
Tidevex quick reference
| Detail | Value |
|---|---|
| Zone | Old Cistern — Lower Flooded Chamber |
| Map position | Grid D7, roughly 40 m below the main walkway |
| Spawn window | Night cycle only, in-game 21:00–04:00 |
| Precondition | All 3 brine lanterns lit |
| Respawn timer | 2 in-game days if missed or released |
| Difficulty | Hard — red-tier catch meter |
| Bait | Glowmoth Lure (or any luminous bait) |
| Minimum rod | Reinforced line, 12 kg test or higher |
Anything below 12 kg test snaps during the second phase of the fight, which is the single most common reason players lose Tidevex after it finally appears.
Where Tidevex spawns on the map
The Old Cistern sits on the western edge of the mid-game map, unlocked after you finish the Pump House errand. Tidevex has one spawn point and no alternates. From the Cistern’s fast-travel anchor:
- Walk east across the broken walkway to the first brine lantern and light it.
- Drop through the collapsed grate at the far end onto the middle ledge. The second lantern is mounted on the wall to your left — light it before continuing.
- Follow the ledge south to the rusted ladder. Descend two sections to reach the lower floor.
- The third lantern is on the pillar at the room’s centre. Light it, then take the submerged stairwell down into the flooded chamber.
Tidevex surfaces in the deep corner behind the fallen column — the pool that reads slightly brighter on the water’s surface. The wider, shallower half of the chamber holds only common Cistern fish and is a frequent time-waster. If your cast lands where the water reflects the ceiling rather than the column, you are in the wrong pool.
Avoiding the two common misses
- Lighting order does not matter, but all three must be lit in the same visit. Leaving to rest and returning resets the lanterns.
- The spawn only registers if you are standing on the submerged stairwell when the clock passes 21:00. Waiting on the middle ledge does not trigger it.
Spawn times and how the window works
Tidevex appears between 21:00 and 04:00 in-game, and stays until you leave the chamber or the clock passes 04:00. There is no partial spawn: either the ripple animation is playing in the deep pool or it is not. One in-game hour equals roughly two minutes of real time at default settings, so the whole window is about fourteen real minutes — plenty, provided you are already in position.
If you miss it, Tidevex will not return until two full in-game days have passed. Sleeping at the Cistern camp skips the wait but also relights nothing, so plan to redo the lantern run when you come back.
Catch requirements in detail
| Requirement | Minimum | Recommended |
|---|---|---|
| Rod | Reinforced rod | Any rod with line upgrade slot |
| Line strength | 12 kg test | 16 kg test |
| Bait | Luminous bait | Glowmoth Lure |
| Reel timing | — | Reel in bursts of ~1.5 s, release on the red flash |
| Attempts before line damage | 2 hard pulls | 0 — back off early |
The fight runs in three phases. Phase one is a straight pull. Phase two adds a red flash every few seconds; releasing the reel during the flash is mandatory, not optional. Phase three is a short stamina burn where Tidevex darts toward the fallen column — steer it away from the column or the line snags and breaks. Players who lose Tidevex almost always lose it here rather than in phase one.
Step-by-step: a clean Tidevex run
- Travel to the Old Cistern anchor at dusk so you arrive before 21:00.
- Light all three brine lanterns in one pass.
- Descend to the submerged stairwell and stand in the water, not on the ledge.
- Wait for the ripple animation in the deep corner pool.
- Equip luminous bait and a 12 kg+ line before casting.
- Cast into the ripple, then reel in short bursts and release on every red flash.
- In phase three, pull away from the fallen column to keep the line clear.
Common questions
Does Tidevex spawn in the rain?
Yes. Weather has no effect on the spawn; only the time window and the lit lanterns matter.
Can you catch Tidevex more than once?
Yes, on the two-day respawn timer, but only the first catch is needed for the Cistern ledger entry.
Is Tidevex required for anything else?
It is one of the four fish needed for the Old Cistern completion set, and releasing it instead of keeping it delays that set by two in-game days.
What if the ripple never appears?
Nine times out of ten a lantern went unlit, or you were standing on the middle ledge instead of the submerged stairwell. Re-run the lantern route and check your footing before assuming a bug.
