Why did they stop breeding?
 

My clowns had an anemone at the back of the tank, where they spawned like clockwork every two weeks. This went on for six months or so, then they moved to a much larger anemone at the front of the tank. They have been there about six months and haven't bred once. What would cause this?

Had a similar problem several years ago and found that in the new location they were getting out competed for food by the other tank inhabitants so they were eating quite a bit less. Once I started feeding them separately with a baster twice a day they began breeding again within the month.

Could be other things as well like a suitable substrate, water flow, lower temp but you may want to assess their eating habits first.

Thanks Reno!