It is a dorsal-less fish – good specimens will have a clean back and eye bubbles that match in color and size.

If one of their "Bubbles" pop due to pressure or collision with a sharp object, there is a risk of infection where the inside of the sac has been exposed.

[6][7] Through selective breeding, the bubble eye is currently available with either a long or more rounded body and the choice between matte, metallic or nacreous scales.

However, due to the fish's visual impairment, it is recommended that they are kept with other bubble eyes, black moors, demekins and celestial goldfish to ensure fair competition for food.

[13] Due to the eye sac's ability to quickly regenerate and refill itself, scientists can milk the same fish every few months with a syringe.