a single gilded koi fish close-up, traditional Chinese ink wash painting style, xuan paper texture, black ink brush strokes, soft ink diffusion, elegant gray wash, subtle gold leaf accents on koi scales, flowing water ink wash background, refined guofeng artwork, large negative space, poetic composition, natural koi eyes, small simple black koi eyes, eyes proportional and aligned, delicate fish head anatomy, museum-quality oriental art, restrained palette, high detail, no text, no watermark