My male swordtails intentionally swim backwards into the females. is this part of courtship or something else?

i have 3 swordtails, 1 male and 2 females. the typically persistent male never leaves the one female's side. he performs this strange ritual in which he stops dead in his tracks and swims backwards into the female as though he is trying to poke her with his tail. i thought this was just some sort of courtship ritual until i noticed one of the 2 week old fry in my tank doing this same sort of thing to another fry. i'm somewhat perplexed because i'd read that swordtails don't develop a gender let alone a desire to mate until well after the fry stage. i'm just really curious about what this ritual is for because it doesn't seem isolated to just mating based on what i observed with the fry. is it a territorial thing perhaps or can the mating instinct happen much earlier than anticipated?