Couple of questions re new goldfish tank, and also behaviour

[Duce]

So I have a new tank which I will begin cycling hopefully tonight (Juwel 350 in case it matters) and wanted to confirm what I was told by others. I was informed that it is ok to add some fish (My tank will be a mix of black moors and fancy goldfish) to the tank on the first day after filling it to help in the cycling process, is this correct or should i hold off on adding fish too soon (Was thinking of adding 1-2 fish, but will that create problems due to territory when others finally added?).

Secondly regarding water for the tank, i was told by the store that tap water is fine, do I need to get any removal agents at all? and can the tank be filled via a outdoors hose (My last tank was filled by the store which is why i'm unsure sorry).

Finally I'm curious on this behaviour from one of my fantails who is slightly bigger than the newer arrival to the tank (Also a fantail). I put the new fish in last night (Bio orb 60L, has been running since Aug with only the existing fantail in it as the other fish got sick, removed to QT tank and died back in early aug, think the fish was sold not well) and it initially was fine, then the existing fish has began nipping its fins.

I had added alot more decorations and moved the existing ones around to try to stop this. but it seems the existing fish nips at the newer one at times and sometimes follows it for a short distance to nip it again, but then swims off.

The new fish is pointing its head to the top of the tank and wiggling on the spot slightly leaning back when the other fish comes close. Is this submitting behaviour to the existing fish?

I'm hopeful when both are added to the new tank they will get along as it will be a totally different setup and much bigger.

Anyone able to help identify this behaviour for me?

[emc7]

Don't mix one and two-tailed fish. The fish with a normal body type have a huge advantage in speed and maneuverability and likely will eat most of the food and if there is aggression, it won't be a fair fight.

I would recommend a dechlorination such as Pond Prime. If you have only chlorine and not chloramine in the water, a lot of it will evaporate in a pond, but why take a chance?

If the fish looks up and wiggles when you look in the tank, he is waiting for food. If he does it when you are out of sight, I don't know what it means.

[Duce]

Thanks for the reply, all my fish are going to be fancy goldfish for the tanks (plus black moor) so I assume this is ok regarding tails?

Got the tank cycling last night and added some dechlorination as you mentioned.

The fishes seem to have calmed down now which is good, think removing all the decorations helped a little (moved them to new tank and more will be added to older tank to break up the territory).