Green Chromis Damsel (Chromis viridis) grows up to 3 inches. General Size Specifications: The small size will come to you generally 1 to 3 inches; the medium generally 1 to 3 inches; the large generally 1 to 3 inches. Minimum Tank Size: The Chromis (Green) Damsel prefers a tank of at least 30 gallons with plenty of places to hide & swim. Diet: The Chromis viridis is a omnivore and likes to eat variety of foods (meats & veggies). Level of Care: The Chromis (Green) Damsel is a low maintenance fish.