Halo fish

Halo fish

The Halo fish is a type of sensitive lab-animal kept in Sickbay onboard the USS Enterprise. This species of fish, which is normally surrounded by a bright glowing halo of light, loses all color at the smallest environmental change.

In 2269, Captain Kirk called Sickbay to see if the X-waves the ship was just probed with had any effect on the sensitive lab animals. Nurse Chapel reported that the Halo fish were glowing as bright as ever.

Once the crew and all organic material aboard ship began to shrink, it was observed by Chapel that the Halo fish have shrunk to tadpole size. (TAS: "The Terratin Incident")