Another dead fish

[Lydia]

Well, after my flag fish died, now one of my male platies died (well, almost...he is in a cup of water but there isn't any way he's gonna make it...I should probably just euthanize him). This one I've had for 1 1/2 years, and the last 4 months he has been more lethargic. The last 2 weeks or so he has been having a little trouble swimming. The last week he got a white spot on his head, which I just figured was either an abrasion or something like that (it wasn't ick or any disease that I know of). Today after I got home from work I didn't see him when I looked in the tank but I figured he was just hiding. Tonight I looked over at my tank and he was swimming sideways and upside-down, and when he got into the flow of water from the filter he was swept away by it. I caught him after a little bit of trouble (he was still well enough to try to swim away from me) and I put him in a cup of tank water, so if/when he dies he won't foul the tank water. When I went and looked a minute ago he was on his side. I thought he was already dead, but when I tapped the side of the cup he moved his fins a little. I guess I will probably euthanize him.

Anyways, I'm just wondering if this might have anything to do with the death of my flag fish, or if it sheds any light on it or anything. I guess it sounds like a stupid question, but I am just trying to make sure there isn't something majorly wrong in my tank.

Here's the link to the thread about my flag fish. It has all the info about tankmates, params, etc. http://www.fishforums.com/forum/showthread.php?t=10086

Thanks in advance for any help!

[emc7]

If one fish dies, its bad luck or old age, if two fish die its either water quality, aggression, or disease. Sometimes one dead fish will cause an ammonia spike, but you changed water after the death, so thats not it. Unless your kribs are spawning, I think it is probably some disease I never heard of. I have one tank (out of dozens) where most of the fish have died one by one several weeks apart. I'm feeding the survivors medicated food, in case its an internal parasite. An internal parasite would fit with the flag fish looking thin, but showing no external symptons.