Krishna Cleans the Aquarium

It's time to clean the family aquarium! Kimberly is still a little too young for such an important family task, so her older sister Krisha is going to step in and handle this responsibility. She's very responsible, too. Everyone knows that the fish will be very safe with Krisha handling things. If Kimberly cleaned the aquarium, many of the fish would be in her stomach instead of back in the aquarium. Krisha is much more trustworthy... or is she? There are four fish when she starts working. How many are left when she's finished?