Unexplained Barb Deaths

Sorry to report two of my larger 5 band barbs have given up the ghost, I found one yesterday that maybe had been dead for a day, and today another one that looks to have just died literally before I got in from work.

I gave them a good looking over after I found the first one, but nothing seem awry although I think the one that died today was just sitting on his own last night so I did wonder if he was poorly, but I'm surprised at how quickly he died.

Water parameters are as normal, and 50% water changes weekly, next one due on Friday. So I suppose it might just be one of those things, however is there anything I should do, other than keep an eye on the rest of the guys?

Thanks

Fish do sometimes just die, and we never find out why. The best thing to do is an extra water change, cleaning the substrate as much as possible.