We have dual hot water heaters - both 40 gallons that somehow work together. One was leaking yesterday, so we got it replaced today. When we turned on the hot water at the faucets, there was a lot of gurgling, etc, which I know is normal, since all the water had been drained. However now, the hot water is cloudy and almost fizzy when it comes out, and the cold water is not. Is this normal? I just want to make sure that everything was installed properly by the plumber and this is not another issue.

Cloudy water's caused by air bubbles in the system, hence your "fizzy" hot water. This could be caused by cavitation in the heat trap nipple,(see image) located on the hot water outlet side of the water heater if you have them installed. I would give it a day or so to see if it worked itself out and call the plumber back to replace the heat trap nipple with a brass one.
Good luck and thank you for rating my reply. Tom