I've had 3 little corydoras since I started my tank up last year and all have lived quite happily together, yesterday though I found one of the poor little things not well at all, as the title suggests the best way I can describe it is that it looked like it had, had a stroke. It was finding it difficult to swim and kept swimming on its side and upside down. It was upsetting the other 2 so I isolated it but it sadly was dead by this morning. Any ideas on what it could be it was just rather strange, showed no prior signs of anything wrong. 
Thanks in advance
Thanks in advance
