Goldfish fighting

[Linny2 0]

Hi there,

 

I have had a calico fantail on it’s own for 6 weeks in a 32 gallon tank. He is vert small. 
 

today I added a ryukin which is about double the size of the fantail. The fantail has been chasing the ryukin non stop since I added him to the tank. The ryukin does not seem stressed but I think the fantail is sometimes nipping. 
 

im not sure why a smaller fish is attacking the bigger one. I turned off the lights and moved some decorations. Nothing is helping. 
 

will this behaviour stop over the coming days?

 

any advice would be great. 

[shakaho 6,312]

It sounds like spawning behavior.  The odds are very good that the fantail is a male and the ryukin is a female.