Roe on sushi refers to the use of fish eggs as an ingredient or garnish in sushi dishes. In the context of sushi, "roe" means the fully ripe eggs of fish or marine animals used to add texture, flavor, and visual appeal. Several types of roe are commonly used in Japanese cuisine, especially in sushi:

• Ikura: Salmon roe, large, bright orange eggs with a salty, umami flavor. Often served on sushi as gunkan-maki or as a garnish. They are marinated in soy sauce or salted to enhance flavor.
• Tobiko: Flying fish roe, small crunchy eggs naturally red-orange but sometimes colored green (wasabi), black (squid ink), or yellow (yuzu). Used for garnish and added texture in sushi rolls.
• Masago: Capelin roe, similar to tobiko but smaller, also used in sushi.
• Other varieties: Shrimp roe (ebiko), herring roe (kazunoko), cod roe (tarako, mentaiko), and sea urchin roe (uni) are also enjoyed in sushi and Japanese dishes.

Roe enhances sushi with distinct textures ranging from crunchy to creamy and provides bursts of salty and umami flavors. It is a prized and traditional ingredient in sushi culture, contributing both taste and aesthetics to the dish. In short, "roe on sushi" means fish eggs used raw or marinated as a flavorful and textural component on or in sushi items. The most common roe in sushi are ikura (salmon roe) and tobiko (flying fish roe).