How to reach the Pearl Gourami spawn
Stay in the shallow lake
Do not descend into the deeper ruins or Lakebed Sea; the gourami is an Upper Lake species.
Follow the Black Caiman route
Use the predator's chamber or nearby passage as the key landmark.
Search the water behind it
Inspect the calm pockets and vegetation after the dangerous section rather than stopping at the arena.
Return on a fresh dive if needed
A complete route with no gourami is faster to reset than to extend into the wrong biome.