Is This Common?

[sotik]

If any of you read my other post you know I have a 20 gallon tank with two zebra danios in it. I have them in there to help with my fish-in cycle however I have been watching them and at first they were swimming around like pals, like schooling fish should do, but now it seems the bigger one is just constantly chasing the smaller one around the tank. Is he just trying to establish a pecking order, is he trying to kill the smaller, is the bigger one trying to mate with the smaller one? Should I be worried or is this normal fish behavior?

Thanks.

 

[OldMan47]

Zebra danios chase each other constantly. It can be a breeding behavior but the big one chasing the little one is a bit unusual. The females are usually considerably heavier looking fish and the males chase them, not the other way around.

 

[waterdrop]

Zebras are not shoaling fish per se, but my own feeling is that they can exhibit more chasing and harassing behavior as their number drops below 6 and additionally if the tank is less than 30G/114L. I may be reading too much into it but this is my take.

Not sure if the others here would feel we should stay at 2 danios or if 3 would still be ok for cycling a 20g. 3 might be slightly better among them for the distraction effect.

~~waterdrop~~