The unique AHAB nursery system uses special mesh-bottom tubes that fit neatly within special 3-litre and 10-litre lids. Two fit in 3-liter and four in the 10-liter tank. Nursery tubes provide an ideal environment for zebrafish fry, while maintaining excellent water quality by diffusion. Food is concentrated within a smaller volume for maximum growth. Tubes include tube lids and locking rings.