Odd fish death

[dsaundry]

Had this happen before. Both in f/w and s/w. Fish were happy and seemed to be ok the day before. No apparent reason for death. Water changes done regularly and water tests were ok. One question, when you do your tank top ups do you fill tank right to the top? If you have a covered tank this may cause a lack of oxygen in tank, learned that lesson with some f/w angels, lost 18 in one night. If you have tested all your water and all seems ok, unless you start to see fish float again I would probably say you have done all you can do to this point. Sometimes stuff happens. I would also add make sure you check tempurature and maybe even for electrical charge in water too. All could cause problems without affecting water quality. Good Luck.