Martin, you are fully right in comparing Calcium and Natrium. Our fish are not accustomed to Ca, not at all. But they stand (or even need) a certain amount of Na. Think of fighting oodinium by Na, an old method. There are better methods today, but if you are uncertain about the real pest or illness, giving a rather high concentration of Na will often help the fish to survive and get healthy again. This would never happen with Ca. That mineral must be avoided at any rate. It’s one of the main reasons why our tap waters are badly suited for keeping or breeding black water fish. At least if not treated by the well-known methods that remove the Ca.
The
PAROSPHROMENUS PROJECT
