Can fluid in ears go away without placing tubes in ears?

Yes. In children, persistent fluid in the middle ear can resolve at any time after an infection; however, the longer it persists, the lower the odds that it will resolve on its own. Particularly if the child has recurrent infections, or shows signs of hearing loss, tubes may be necessary.
Maybe. Infants can have fluid off and on for up to 3 months and clear without problems. Those that experience middle ear infections can and do clear sometimes.Yet those having several rounds of abx that fail to clear in infection can have fluid turn the consistency of axle grease, and never clear without help.Tubes in infants are often placed after the muck is removed.
Ear tubes. Sometimes fluid will resorb on its own. In kids, we can wait up to 3 months to see if it will resorb, providing it doesn't get re-infected. For adults, the sensation of fluid is so annoying that they often don't want to wait more than a few weeks. I usually offer simple drainage first, then a tube if the fluid recurs. I also check the back of the nose to make sure no there is no mass on eust tube.