Balas will need a 2 metre long tank before you know it. They are also a schooling fish, so if you can house them at all, you ought to get another 3. Goldfish
need no less than 80 litres each (and some would tell you 100), and prefer cooler temperatures (18 - 20 C).
So with 5 fancy Goldfish
, you're looking at a 400 to 500 litre tank.
Actually, you could keep the Hillstream Loach
with your Goldfish
(though it would really benefit from more current than fancy Goldfish
can handle), and maybe the danios (they can handle 20C)
The tetras not so much. They need a temp 24 to 27C.
And the Pleco.... That's a half meter of fish before it's done growing. It'll be 20cm in a year. That would do fine in a tank that would house the balas.
So, to recap - the tank you have would be fine for the tetras, and that might be a good place to start on a softwater tropical tank.
will need a 400 liter or more tank. If you go with one around 500 litres, you could put the danios and the loach in there too.
The Balas need a 2 meter tank and to be in a group of six, and the pleco should go in that tank as well.
Your mileage may vary, but not by a whole lot.