Fish, especially a goldfish like she keeping as aquarium fish. She had wondered how goldfush feels. She thought it would be good to be a goldfish, and experience how her goldfish feels.
But... what if she couldn't be human back? Given that there was a 'return' vial, the strain seemed to be transform until drinking it. It was surely impossible for goldfish that could not come out of the tank to drink vials. She wanted a lot to be a goldfish, but she also didn't want to no return human back.
She got an idea. If she doesn't have the full vial, it wouldn't change her into fully goldfish. However it could risk. The amount she drink and hiw much of transformation may be not related.