Crab roe is used in some sushi, and they may have been soaked in food coloring to change their color. For example, black crab roe may be soaked in squid ink or other black food coloring to give them a black appearance. Similarly, red crab roe may be soaked in shrimp juice or other red food coloring to give them a red appearance. These dyed crab roe may vary in color and taste, but they are still safe to eat.

Overall, crab roe, whether natural or artificial, can be eaten as part of dishes such as sushi, as long as they have been legally manufactured and stored under proper conditions. However, if you have any concerns about the source or color of crab roe, it's best to do some research and confirmation before consuming it to ensure its quality and safety.