Does fluid draining from my baby’s ear mean he has an ear infection?

Not necessarily. 2 conditions can result in "fluid" draining from a baby's ear(s): the first is an infection in the ear canal ("otitis externa"); the second is an infection behind the ear drum ("otitis media") that has come through the ear drum and is draining. Some baby's simply accumulate some small amount of bath water in ear canal. If the fluid is not clear, or if the fluid smells bad, get to your doctor.
Most likely. The fluid can represent a middle ear infection which either caused a perforation of the ear drum to release pressure or oozing of fluid through the ear drum. This is particularly suspect if the baby recently has had an upper respiratory infection. Less likely, the fluid can be due to an external otitis(swimmer's ear) where water collects in the ear canal resulting in inflammation and pain.