Zebra Danios Getting Territorial?

Hey! I bought a 20 gallon tank about one week ago I have had it running for 7 days (I added bacteria starter on day 1) I tested the water and I got 0 Ammonia 0 Nitrite and 0 Nitrate. I was told that I’m fine to add fish so I got 6 Zebra Danios ( 3 Regular and 3 Long fin Gold Danios) I added them last night and left the light off until today morning. I woke up and fed them and everything seemed normal but now I’m noticing that all the Long fin gold danios are getting very territorial. The other 3 are perfect but the long fins are at the bottom all holding down a different spot and when other danios enter the area they chase them out. Is this normal? It has only been about 16 hours since I have added them! I know I have lots of space for them but don’t understand why the long fins are behaving like that. Can anyone please help?

 

Look up a fish in cycle. That is what you will be doing.

Letting a tank run 7 days with only bacteria starter will do nothing to cycle it unfortunately. There needs to be an ammonia source. You have it now from the danios.

Danios have a heirachy of dominance, chasing and a bit of territorial behaviour is normal.

 

One of the appealing aspects of keeping Zebra Danios is that they constantly & harmlessly chase each other around the tank.
Be careful & continue to closely monitor your water parameters. Quick start bacteria products tend to be over rated & often have very limited success.

 

One of the appealing aspects of keeping Zebra Danios is that they constantly & harmlessly chase each other around the tank.
Be careful & continue to closely monitor your water parameters. Quick start bacteria products tend to be over rated & often have very limited success.

My concern isn’t really the chasing off it’s more of the danios staying alone in one spot and not letting any other fish enter the territory. Would that be an issue?

 

That's certainly odd behavior for Zebra Danios, but not overly concerning. As long as the fish are eating & no damage is being done to fins, likely no worries.

 

Update: I returned the 3 long fins and went with the regular and now they are all doing perfectly fine! Thank you all!