Bashypack- theres probably something you need to know about whitespot. You never know , it might help you next time.
Whitespot is a common parasite around tropical regions of the world, it exists both sides of the equator , and is spread in both segregated lakes, and connected river systems, as such although still considered one species, it is subject to a certain amount of respeciation and there are as a result, different strains. No one medicine will kill all strains of whitespot, even the usually reliable protozin has its limits, but I have generally found that what protozin cant kill, esha exit will, that is of course assuming what you had was actually whitespot.
There are a few diseases that look like whitespot, many small burrowing flukes can give the look of whitespot, then theres gold dust disease, and even some bacterial reactions in fish may produce many small pustules that to the uninitiated eye may look superficially like whitespot.
Then there is the fact that whitespot kills by its drain on the host, sometimes if the coverage is vast, the first generation of adult whitespot parasites may kill the host, and even under immediate treatment it can sometimes be too late, It really depends on the owner spotting the spots before they become too numerous.
Then, also worth bearing in mind that most protozoan parasites (sporozoan in this case)also reduce the immune system of the host, making other ambient bacteria more deadly to the host. Its not unusual to find that you have treated whitespot successfully , only to find the fish fall to other common bacteria, for which real antibiotic treatments are more appropriate. Its actually usual rather than extraordinary for a fish sufferring these parasites to also have other complaints. Fish getting whitespot obviously havent been subject to good quarantine, and that means any one of hundreds of other diseases can be in the same tank, just ready to bloom when a parasite hits.
Gimme the run down on everything that you did, every symptom you saw on the fish, and I will probably be able to work out what happened, why it happened, and how to prevent it from happening again. If you posted on the subject, pooint me in the right direction. ;)