Death!

[TwoTankAmin]

Well- you can try either a worm med or a parasite med and not have to worry about ill effects. However, that doesn't mean the fishwont die during treatment. However, it most likely would not be due to these meds.
 
Its just that its hard to believe they came in that way as I would then expect the breeder to be having similar issues as well as his/her other other recipients.
 
I know this doesn't help, but over the years I have had bad experiences with fish dying and never being able to figure out from what. I had a 20 long than ran great for about 18 months- assorted fish, spawning Montezuma swords. I an then one day things started to die. Every few days one or two dead fish. Anything and everything in that tank, except the bn plecos would die. I treated with anti-biotics, anti-parsitics, anti-fungals several times over a 2 year period. I even considered sacrificing a live goat.
 
Ant then as suddenly as it all had started, it stopped. And a couple of years later the tank was upgraded and the fish moved. To this day I have no clue what was wrong in that tank.

 

[This Old Spouse]

I think you know what happened in my tiger barb tank with the deaths. I'm still not positive what happened, but I think it had something to do with moving a bunch of plants around and disturbing the substrate. There's nothing else that makes any sense. 

 

[snazy]

My experience is the same as TTA's. Once you get sick fish, it's hard to figure it out and in my case it's always been a long and hard process.  I've got problems twice over the years and both times it took many months to sort it out and numerous meds without much result.  The first time I had no idea why they got sick but got lucky figuring out what they were sick from and finally one of the meds worked out after 3-4 months of trying. The second time(only recently) I knew the cause, but no medication seemed to work to treat the subsequent disease. I even checked one of the dead once under the microscope and found zilch.
Prevention is the key....
It sounds easy on internet when one reads symptoms and then the possible treatments but many of the symptoms are similar for multiple diseases and many of the meds just don't work as intended. Too much bacteria and parasites seem to have become resistant to the off the shelf medication and many of the medications will do more harm than good if dosed inside the tank.
 
From your description, my guess would be bacterial/fungal infection due to the fish not flashing. Normally with parasites they feel really annoyed and go around scraping themselves off the decor. But that's a wild guess.

 

[eaglesaquarium]

Well, it makes sense, just like "Legionnaire's disease".  Living in a cramped environment with little "ventilation" is going to cause it to spread like wild fire - that'swhy water changes are so important.  But honestly, unless you can do a continuous change 24/7, you won't be able to fully stop it, probably.  This is certainly not the case all the time, but certainly in some cases with communicable diseases, it can just happen and there's not a lot you can do about it, but hope for the best and that it only affects certain species.

 

[LeahMay]

I do apologise for not responding any sooner, i myself have been fighting off my own infection.
Unfortunately one by one the penguin tetra died, the other fish have all survived and so the cause is still completely unknown to me! Luckily it was just my penguins, I'd have been more annoyed if it had took my whole tank down with it! 
RIP little fishies! 

Thank-you to everyone who helped me in my time of need.