That is something I have never measured. I have only tested for PH, Ammonia, Nitrite and Nitrate. Im taking it to the LFS today to double check my readings, Ill ask if they can do those tests for me.
assuming they are not wild caught they should be fine. I have my malawi cichids in a ph of approx 7.8. as long as it is consistant and not acidic (i.e 6) they should be fine