Here are the photos

That branch looks dead...

The one below looks like it's turning brown too but all the new growth from summer is still green.

Here a few more photos

The one above, the trunk looks like it's unhealthy too.

This one is a close up of the branch with some green growth... The last photo shows what looks like a crack in the branch.

That is such a big container for such a small tree. Equals problems.

Check the roots and see how they look. If the roots look good, how much space is between the rootball and the edge of the pot? You only want 1-2". Are you watering only when the top 1-2" of soil is dry? A lot of citrus drop their leaves when there is an environment change. Did you slowly acclimate the change when you brought it in?

Hate to tell you this, but if you want to save the tree remove the fruit. The fruit is draining energy away from the rest of the tree. When was the last time you fertilized? What's the mix the tree is planted in?

I can agree that the container is too big, I know the root ball was tiny compared to the pot.... this was in the Spring when I placed it in this pot. I water the limequat less than I do other trees and Yes, I do the finger test. I'd hate to have to repot now in the middle of Winter... It was growing fine during spring and summer... Yes, I fertilized it last in Mid December.

I would check the rootball then to see how it is.

Dave, I would defintely trade that pot for one that is one size bigger than the root ball if you are going to use a more moisture retentive mix. Asap.

While you are at it check the roots. So both Denise and Silica are dead on)

Mike