The porcupine needs 450 litres, would probably add 100 litres to allow for other fish, if to put a dog face in there as well an extra 380 litres? Or like say a dwarf puffer tank (first is 5 gallon then following extras 3 gallon) what would be the minimum for a porcupine and dog face?
It is only idea stages at the moment, costing up and looking into the sorts of fish my partner would like to add to make a community tank