Bristlenose Pleccos behaviour

[BarbsandGobies_expert]

Hi, so I've been keeping bristlenose pleccos for a while now, I had a female for quite a while but I recently got a pair of younger pleccos for my aquarium. I've done some research on breeding behaviour and mine are quite peacefully getting on but also conform to a mating behaviour, vigorous swimming but also a vibrating next to eachother. There too young to sex them yet and may just be the same sex.
Does anyone have experience this bristlenose and recognise signs of mating?

 

[ghyti]

The vibrating next to each other is fighting for the best spot. Even at a 1/2 inch they will fight. They are cave spawners. The male will stay in the cave and wiggle his tail to attract females. The Female will stay as far away from the cave as possible. When she is ready to spawn she will get closer and closer to the cave. Finally she will go in and they will spawn. 5 days for eggs to hatch, 5 more days for them to use up egg sacs and be ready to start coming out of the cave to eat. They are old enough to spawn when the male develops bristles.

 

[BarbsandGobies_expert]

The vibrating next to each other is fighting for the best spot. Even at a 1/2 inch they will fight. They are cave spawners. The male will stay in the cave and wiggle his tail to attract females. The Female will stay as far away from the cave as possible. When she is ready to spawn she will get closer and closer to the cave. Finally she will go in and they will spawn. 5 days for eggs to hatch, 5 more days for them to use up egg sacs and be ready to start coming out of the cave to eat. They are old enough to spawn when the male develops bristles.

Yeah, I will eventually set them up with a cave, vibrating can also mean breeding displays which is another possibility as one has slightly branching bristles indicating a male.
However they were just put in the tank so you may be right that it was territorial although they have settled down now.
If there are fry, though how long does the male guard them and will they be safe in the tank on their own?
(The fish I have in my tank alongside my pleccos are listed on my profile)