SeaWorld said today it will only know the exact cause of Kyara's death after a post mortem, but she had an infection, most likely pneumonia, and her health declined in recent days.
SeaWorld says it may take several weeks to conduct a necropsy.
The water park said during the few months of Kyara's life, she touched everyone that came in contact with her.
Kyara's birth in April was hailed and highly publicized. Officials said the mother has returned back to normal after her daughter's death.
Kyara's mother, Takara, was pregnant when the company announced it was ending its captive breeding programme.
It plans to phase out its reputed live orca performances by 2019, especially after scrutiny was intensified by the 2013 documentary "Blackfish".
Kyara died surrounded by SeaWorld staff.
Tilikum, which sired 14 calves over almost 25 years in Orlando, died of bacterial pneumonia in January.
Two of the deaths happened at SeaWorld Orlando, a man who trespassed into the park and Tilikum's trainer Dawn Brancheau who was killed in 2010.
The next youngest, Amaya, was born in late December 2014.
On Monday, Oscar-nominated actor James Cromwell was arrested at SeaWorld in San Diego during a PETA protest of SeaWorld, Variety reports.
The incident has caused animal rights activists to speak out against SeaWorld.
SeaWorld, which has not captured a wild orca in more than 40 years, now has 22 orcas left in the United States.