It's good fishing in troubled waters.

The saying suggests that confusion, conflict, or instability can create opportunities for someone willing to take advantage of the disorder. The imagined fisherman benefits because disturbed water makes conditions favorable for a catch.

It is usually a critical observation about profiting from other people's difficulties rather than a recommendation to cause trouble. The phrase can also describe opportunistic action taken when normal rules, attention, or resistance have weakened.

Use it when disorder gives an opportunist an advantage, especially in disputes, crises, or organizational confusion. It may describe a person exploiting an existing situation, but its figurative implication is often disapproving and can sound accusatory if directed at someone personally.