Extremely flavorful Bio-pure blood worms are an excellent natural protein source for all types of tropical fish. Standard Blood Worms are ideal for small- and medium-sized fish. Jumbo Blood Worms, which are up to 2.5X larger than standard blood worms, are perfect for big carnivores or monster fishes. Both varieties of Hikari Bio-Pure Frozen Blood Worms are gut-loaded with bio-encapsulated multi-vitamins to support immune system health. Both varieties of blood worms also undergo 3-step sterilization to ensure unequalled product quality - no harmful bacteria, parasites, or foul odors