Why are these old clowns fighting?

[Mr Bojangles]

so I have had these two percs that have been living together for two years now and for the past two weeks they have been fighting chasing each other around. Has this happened to anyone before? Will they stop?

 

[GSMguy]

"old clowns" what do you mean old clowns?

where did you procure them?

 

[Mr Bojangles]

I mean old as in they have been living in the same tank together hand out all the time.

I think I got them from a LFS where they keep about 20 clowns in the same tank

 

[GSMguy]

are they the same size? sorry about that i didnt see that you had them for two years in your origional post.

how bad is the fighting? describe the interaction.