Spawning or attacking?

I have three (five) fish. Only the three matter in this scenaro.

The Oranda will go over the the goldfish, and headbutt him. Then the
goldfish will give a bit of a butt to the shubunkin under the tail,
the goldfish and the shubunkin will have a bit of a wrestle, then the
shubunkin will go have a bit of a wrestle with the oranda. Then the
oranda will go over to the goldfish and have a bit of a wrestle with
him. This all occurs very quickly, and the cory's are just having a
nibble. I've only noticed this after feeding, but there's plenty of
food on the tank bottom. It could be territorial, but the fish seem
to chase each other to the biggest food source, then swim off (not the
other way round)

I find this confusing. Am I likely to hear the splashing of tiny
fins? Or are they being playful? I'm keeping a close eye on them, and
their fins & scales are in perfect condition (no nibbling). The plant
is being eaten to death though, and I'm probably not feeding them as
regularly as I should (the plant is a buffer should I forget) I feed
them once/twice a day with flakes, cucumber, corgette, odd bit of
garlic, floating pellets (which I wait till they are nice and squishy,
then squash them so they sink) peas, bloodworm etc