Zebra Danio behaviour
Hi guys and gals
Hope you can shed some light.
I am new to Danios having never kept them before. I have a group of 7 in a 240l aquarium helping me me cycle it.
Up to now its going well and my water chemistry is spot on
This morning they are behaving oddly
They have started 'chasing' each other but in a weird way. It's almost as if one is displaying to the other. All fins are fully up, one chases another until he touches and then turns around and then the other fish chases until they touch again and so on and so on.
It like game of tag with only 2 players!!
If any other fish comes close they get chased too.
It is tending to be in the middle of the tank and the same fish seems to be involved (just the partners keep changing)
Is this territorial behaviours, aggression, establishing hierarchy, courtship?
They have been so peaceful till now
P.s. please let's not get into the fish in/fishless debate. I know the arguments and as mentioned my chemistry is bang on at the mo.