Rainbow fish

Rainbow Fish is a members-only item on the OSRS Grand Exchange in the weapons category.

In-game examine text: "Well, this would certainly add some colour to a meal."

It has a Grand Exchange buy limit of 6,000 every four hours, a high alchemy value of 72 gp, and item ID 10136.

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Rainbow Fish shows an active flip setup with a margin of +417 gp and 27,377 trades over the last 24 hours.

At the buy limit of 6,000 every four hours, max profit per cycle is about 2.50m gp — high margin with healthy liquidity.