hi Jazz, without wanting to sound mean or nasty i would say nothing.. not just yet anyway,you have had a few problems with your fish latley,and i think you would be better off reading up on fishie illnesses before you go heading in for more heartbreak again,you kept saying you were going to buy a test kit and im not sure you ever got round to it, but thats besides the point ,to me it seems pointless that your wasting your money and your fish like this without finding out just what happened to the others, i know the last lot of deaths (25) was an accident,so look at ways to make sure this wont happen again, stock up on meds,tests,and knowledge,make sure you have every base covered so that nothing like you have been going thru happens again,or if it does your in a position to deal with it fast.
please dont take what im saying the wrong way, but it must be awful to keep losing fish the way you are,and without a testing kit,you wont begin to understand why, there is tonnes and tonnes of info on here and other websites, sometimes its better to take a step back, take it from one who knows from personal experience
good luck jazz
shelagh xxxxx