Tobiko are actually not naturally orange. They are dyed any myriad of colors, usually orange or red, in order to make them more interesting and appealing. They have a slight salty taste that is not fishy and very pleasant.

Ikura, or salmon roe, are naturally orange, however.

Many restaurants of the cheaper sort substitute masago, which is smelt roe, for the genuine article. This is one of the ways you can rate a place. If they use actual tobiko, they are on the way to being good.

Tobiko that has been steeped in wasabi and has an intense green color is called wasabi tobiko. It is quite a nostril clearer. Fans of wasabi tobiko often refer to it as pleasurable pain.