I have a few fan tail goldfish. The lion head is rubbing its forehead under the anus of another fish. It is chasing the other fish all around the tank. Are they mating? If not, what is the behavior?

BTW, the lion head is just 3" long including the tail fins. Without the tail fin, the fish is just two inch long. Its head has just a small patch. When will I see a big mane like crown on this fish? I am feeding them the Oranda Gold brand fish pallets. How can I make its crown grow faster?

The more I looked at it. It probably is not a mating behavior because I have 3 lionheads of different sizes. The mid-size one rubs its forehead under the biggest one's anus, then the smallest one rubs its forehead under the mid-size one. It is like a conga line of goldfish swimming around the tank. The black moor in the same tank does not participate. If this was mating behavior, then the conga line will means a male-female-male or female-male-female arrangement. Either way, it does not look like mating.

I am guessing it is a lionhead's behavior, perhaps the rubbing simulate the growth of the lion head.

Any idea?