item in the image is YEE Methylene Blue, an aquarium water treatment product used to treat fish diseases and purify water.
Brand: YEE.
Use: Treats ectoparasites, fungus, bacterial infections, and white spot disease in ornamental fish.
Function: Purifies water quality and maintains a balanced bacteria colony.
Form: Liquid state.
Warnings: For aquatic animal use only; keep away from children.