Clowns about to mate?

ok i have some clowns that are acting really strange! i have had the pair for almost a year. they have always been buddies i would say. from time to time shimmy againts one another. today i noticed them in the bottom corner going crazy. they would shimmy, one would rub the others belly/ they are resting and swimming near the bottom, the smaller would shape his body almost into a u shape and the other clown had its face resting on the tail area? any ideas? i have never seen them stay in one spot for so long. some gravel/sand was flying around a bit also. they look very healthy.

 

They could be. Mine do that all the time and haven't yet though. I think one of the main things to look for is when they start really cleaning off a section of rock