Black Shuck wrote:

During this whole 2 week episode, I have been doing Nitrite and Amonia
tests, Initially there was a smalling nitrite build up, nothing major,
but nothing else. I have done water changes as a precaution, and both
nitrite and amonia tests were then fine.

As I see it, either my 5 remaining fish die, and a i start again, or
they don't and I start with 5 fish. I have a suspicion that these
problems were introduced into my very stable tank, by some fish I
bought from my local store abotu 8 weeks ago. Perhaps they had
desiese, and it's spread, gathering pace??

That's likely what happened. What an awful experience. I hope your
remaining fish make it.

--
Put the word aquaria in the subject to reply.
Did you read the FAQ? http://faq.thekrib.com