Moreover, using histological examination, the lamina propria (LP) at the tip of the nasal lamella (~ 100 μm away from the apex) showed a significant enlargement (Fig 3C and 3D) and numbers of goblet cells on the nasal lamella increased significantly in the fish at day 7 after infection with Ich (Fig 3C and 3E). This evidence concerns the gene COL4A2 and infection.