Goldfish unsettled and charging

[Belasta]

Hi there,
My mum passed away 2 weeks ago and I have taken her 3 gold fish to care for them.

I bought a new tank Tetra starter pack 54ltr, set it up and ran it for 2 days, cleaned the new gravel with water, and added a water cleansing solution to clean the water.

When introducing the fish, I placed some of their old water to run through the system as well as some of their old stones then floated them for over 15mins before letting them out.

At first they were timid, gravitating towards one corner of the tank, then they went to another corner and stayed.

The biggest one often had moments where he goes a bit crazy then swims back to the bottom and sits.

The concern I have is they originally lived in a 60l biorb which was very crampt but they stayed there for the past year - it wasn't a great unit for large goldfish and often the water was dirty quickly so I originally thought they weren't use to space and clear water.

Now the morning after they were introduced, the large fish is charging the filter (tetra easy Crystal) and looks like he's grazed his mouth and the other 2 are burrowing under filter.

I always kept tropical until past few years (Oscars, plecos, convicts, black sharks) so cold water is new to me.

I'm not sure if the filter might be too loud as the biorb was very silent, they flip out at the light being on.

I've attached a pic and vid to show set up.

https://www.dropbox.com/s/eqsjjqignnwmtah/IMG_20170606_074845.jpg?dl=0

https://www.dropbox.com/s/drkr5p159wwynkh/VID_20170606_074627.mp4?dl=0

The big fish constantly charges the pineapple and disrupts the gravel which is why it's slightly hazy.
The fantail goldfish has burrowed under filter as you can only see his tail.

Thanks in advance

 

[fluttermoth]

Your main problem is that your new tank isn't cycled, so you've almost certainly got a build up of ammonia and/or nitrite; do you have test kits?

You'll need to do some large water changes, and get some of the media from your tropical tank's filter into the goldfish's one to kickstart that cycle.

Cold water is no different from tropical, apart from the temperature.

The fish need more cover, that's why they're being so nervous; cheap, bunched pond plants are probably the best option

I should warn you that, in the long term, your tank isn't big enough. The fantail needs a tank of at least a 100l; the normal ones really need to go to a pond.