XL5 To H2O is the 12th Produced episode and the 7th Broadcast episode of the series Fireball XL5.
Fireball XL5 is sent to help the two survivors of planet Zofeit, who are being attacked by an Aquaphibian, armed with a poisonous gas gun. The crew arrive to find the glass city of the planet destroyed, and no sign of the survivors. The fish man attacks, but is driven off. They find the survivors in an underground shelter, but the creature attacks again. Steve and Venus are just able to drag the survivors away from the poisonous fumes of the gas gun and Steve then uses his stun gun to overcome the beast.
- The Aquaphibian seen in this episode was the inspiration for Stingray's Aquaphibians and even reused the exact same design of body.