Poor lovely fishies..sorry they departed.....
(now you see why the lfs was in error about importance of water quality, the frequency of changes and testing for said quality!). It is not a surprise though, Goldies
really DO require some prep for them to last.
That is why as mentioned earlier in a post..EVERY sitcom with child characters has the ooops! we lost it- and toliet burial of the family goldfish. In truth they are hardy fish with very long lives.....if three main requirements are met from day one. Space-stable water parameters-temp. So any readers considering golds...don't give up!
BTW: Rid Ich is usually a reliable product. It is even highly recommended by several loach keepers at loaches online. And loaches are MUCH more susceptible to meds than regular fish.
Well...now that you are at ground zero....
Since these fish are going to move to big tank later...
And we know your pH isn't neutral or real low; it can even be bumped up by natural method if needed with not too much technical skill.
Cichlids are a great way to go, as it is a large and diverse group.
You could have maybe little cute rams or such or little shell dwellers at the bottom with some interesting bottom feeders like cories
and some appropraite size angel species for the water parameter .. gracefuly moving in the upper levels and a few little schooling fish that are not targets. I don't think tetras would look their colorful best with your water unless you set up a biotope and had peat filters to soften it a bit more for them. and they are busy darting types.
The
FW angelfish are what I had most in mind for your wants for the peace and grace and color you were trying for and the little cichlids of the other body type to add spice.
angels have ton of personality on their own. Graceful in motion they are STILL cichlids and quite the scrapper under that beauty (ask any community betta).
Angels and loaches and cories are what I had specifically in mind for you ...loaches are not JUST bottom feeders but amusing and usually community minded fish in their own right. Cories also are active and funny guys in many patterns. and in the big tank other certain species can be added.