Cichild acting funny

Question
I have had two cichilds in a 20 gallon tank for about 18 months now. The water is okay, temp, everything as usual. One has always gone under a piece of coral and removed all the gravel until it gets to the glass underneath. Now the other one has gone into it's ship-wreck and moved all of the gravel out of it. The one in the ship-wreck is swimming around with it's top fin down on it's back, just floating about and just suddenly ran into the filter, head-long. It approached the other fish and did a little dance, vibrating along side of it. The one acting strange is all yellow with a black top fin, and the other is an albino. Not sure of the sex of either. The one acting strange isn't eating either. Usually when I feed them, I unplg the filter to give them more time to get to the food before its washed away. Upon hearing the filter they usually come flying out of their respective little "homes" and circle like little sharks waiting for the food to hit the water. Today the yellow one didn't come out of his ship-wreck. Maybe 15 minutes later, it swam out and it was then I noticed the fin flat on it's back and it's blah behavior. Any ideas?

Answer
Danielle,

 I would not worry about the gravel moving. Cichlids are known to do this. They will also do this to make a nest for breeding. As for the one with the bent fin, it could have happened while removing the gravel. I would just keep an eye on it and it should fix itself.  The little dance being done is a mating dance. You might have a male and female or 2 females.