The Black Market in Fisch only has a chance to appear during real‑life weekends, and it “rolls” every 15 minutes with about a 75% chance to spawn each time.

Spawn timing

• It is active on weekends only (Saturday and Sunday in real time).

• During that weekend window, the game checks every 15 minutes, and each check has roughly a 75% chance to create a Black Market.

• When it does appear, the shop stays open for about 10 minutes before despawning until the next 15‑minute roll.

How to know it spawned

• A global notification/announcement appears in‑game telling you that the Black Market has spawned and which island it is on.

• The spawn is global across servers, so the timing and stock are the same for everyone while that instance is active.