The Rosy Loach (Petruichthys sp. "rosy") is a tiny, peaceful, and active nano fish, typically growing to about 2.5–3.2 cm. Known for its vibrant pinkish-orange to red coloration in males and a distinct black lateral stripe, it is a popular, schooling species ideal for heavily planted aquariums, often found in the same habitat as Celestial Pearl Danios.