It sounds like you’re referring to "Bangla Ruei Mach" or "Ruei Mach," which is likely a misspelling or transliteration issue. In Bengali, “Ruei Mach” (or "Rui Mach") refers to the Rohu fish (Labeo rohita).

Rohu Fish (Rui Mach)

• Scientific Name: Labeo rohita
• Type: Freshwater fish
• Habitat: Common in rivers and lakes in South Asia, including Bangladesh, India, and Pakistan.
• Description: Rohu fish is known for its mild flavor and is a popular fish in South Asian cuisine. It has a distinctive, slightly elongated body with a silver to greyish color and a forked tail.

Culinary Use

• Dishes: Rohu is used in a variety of traditional dishes such as curries and fried preparations. It's prized for its taste and is a staple in many Bengali meals.