Balance in the tank..?

[George]

Hi, this is george from Bristol in the UK.

Today is a sad day as one of my cichlids has left this earth, completely unexpectedly and without obvious reason. He seemed the healthiest of the three but this morning he was bloated and on his side. He swam around a bit but started excreting milky fluid from the anus and was pretty much done for by the time I prepared the sick-tank. Could this have been dropsy, or maybe another bacterial infection?

I have treated the water with BSB following a water change and filter clean since this tragic loss. Are there any other obvious precautions I should take with the tank?

Also, I am now left with a single Malawi cichlid and a catfish. Providing they do not succumb to similar sudden illness, will they live in harmony or will I need to enlist another cichlid to even the balance? Your advice would be greatly appreciated.

Thanks in anticipation,

George