Zebra Danios old chasing new & different colour!

HI there everyone, I hope you can help me decide if my fish are "normal"...
I introduced 4 ZDs to my tank as first fish about 10 days ago and have just added another couple this afternoon to make it up to more of a school but I have two questions...
Firstly the new ones are much more silvery than the older ones (none were fully grown when I bought them), it makes the old ones look like they have gone rusty by comparison! - is the much more gold colour how they should be? Or do I have some kind of disease? I only introduced them because all test levels were zero - it is a live planted 165litre aquarium and until now only had the 4 small ZDs.
Secondly, although they were all jazzing around nicely together earlier today, this evening all 4 of the old ones are chasing one newbie around the bottom of the tank, are they just being playful or is it something more serious? I'm worried they'll run out of energy
thanks for any news and what to do if this is not normal...PS I don't have any other tanks so can't separate them if I should have to...oh heck
Mel

 

They're getting to know each other.

 

They're okay.. mine do that all the time(just a little play fighting) I have had mine new ones for about a month now and my old ones don't chase them anymore...
I like to think of it as the "initiation period" for the new fish and the school.

Mine still "fight", but eventually you find out who the leader of the school is, and he will set everyone straight...

 

Thanks Psalm and Apple, they must have amazing energy reserves, they've been at it for about an hour - I guess a good nights sleep will probably help too...me, that is, not them, all this fish parenting is wearing me out ;0)

 

The energy will wear you out! Think energizer bunny on caffeine!

 

Couldn't agree more. This sounds like normal behavior to me

 

Thanks for the reassurance guys, really appreciated, feeling much happier now
Do you have any suggestions on the colour at all? They look really orange compared to the new ones, like they need polishing to make them silvery again,

 

My zebras have all different coloring, some blue, some silver, some gold. I think it's normal for ZD to vary in color. There are also purple danios.

 

Thanks for the reassurance guys, really appreciated, feeling much happier now
Do you have any suggestions on the colour at all? They look really orange compared to the new ones, like they need polishing to make them silvery again,

They could be glowlight danios....

could you try and post a picture of them( I know its hard, but a pic would help)

 

Thanks again for the suggestions, I'm pretty certain they are standard ZDs but to try and photo them, well, when I finally get a decent photo I'll post...it's like Psalm said, energizer bunnies on caffeine lol ,
They have also all seemed to settle down this morning, the new ones seem to have taken up residence higher in the tank, so all is relatively calm, for ZDs anyway.
Happy Friday to you all