Used primarily as a dye in the textile industry for coloring silk, wool, and cotton due to its intense green color and good affinity for fibers. Also applied in paper and leather industries for staining and coloration. Historically used in aquaculture as an antifungal and antiparasitic agent in fish treatments, though this use is restricted or banned in many countries due to toxicity and potential carcinogenic effects. Still employed in some regions for controlling fungal infections and ectoparasites in fish farms. Commonly used in microbiology as a counterstain in Gram staining procedures and as a pH indicator in analytical chemistry. Also utilized in the synthesis of other dyes and as a redox indicator in titrations.