Infusoria are used by owners of aquariums to feed fish fry; newly hatched fry of many common aquarium species can be successfully raised on this food during early development due to its size and nutritional content. Many home aquaria are unable to naturally supply sufficient infusoria for fish-rearing, so hobbyists may create and maintain their own supply cultures or use one of the many commercial cultures available. Infusoria can be cultured by soaking any decomposing matter of organic or vegetative origin, such as papaya skin, in a jar of aged water. The culture starts to proliferate in two to three days, depending on temperature and light received. The water first turns cloudy, but clears up once the infusoria eat the bacteria that caused the cloudiness. At this point, the infusoria are ready, and usually are visible to the naked eye as small, white specks swimming in the container.