Trout

Trout is a free-to-play item on the OSRS Grand Exchange in the other category.

In-game examine text: "Some nicely cooked trout."

It has a Grand Exchange buy limit of 6,000 every four hours, a high alchemy value of 6 gp, and item ID 333.

View on OSRS Wiki

Trout shows an active flip setup with a margin of +3 gp and 89,438 trades over the last 24 hours.

At the buy limit of 6,000 every four hours, max profit per cycle is about 18.0k gp — high margin with healthy liquidity.