i have owned the 2 whites pictured left for 5 and half yrs. I done my 50gallon water change as always on sunday morning. All was fine, Ammonia 0 nitites 0 nitrates 30% before and 15-20% after the change. I got home moday morning to find 1 of the whites(pic top) dead and another black tiger very sick. very pale colour,not moving at all. both fish looked in mint condition and were not sick before the water change... this has left me a bit puzzled. 2 other oscars,2 clowns,and a parrot are very well. I have retested water and its the same, fine. temp is around 28c and I always do my water change the same way. Fill large drum, heat to 28c,treat with aqua safe then fill tank. I have treated for internal infection and added aqua tonic salt as fish was very ill and wont last long if not treated. Not sure if there is anymore I can do and took a chance that it was internal. Hes still alive but still very sick,pale. I have not lost a fish in 4-5yrs and was woundering is it possible that a infection can be picked up from a water change??
setup is 150g tank, fluval FX5 filter 4(now 3) oscars around 11"or 12" 2 clowns 8" 1 parrot.8"
I know I am over stocked, I took 2oscars as a rescue 2yrs ago but fell in love with them. i do 2 50gallon changes a wk and test water twice a wk. thought i would write it up to see what you guys/girls think. I have not put up a pic as fish looks fine just very off colour/very pale. dead fish looked fine too.

I'll be perfectly honest with you, I don't think anyone will be able to tell you why the fish died. The only way you'll find out is to carry out some kind of postmortem. You've done your water tests and they seem okay, all the other fish seem healthy. You've got virtually nothing to go on. The best thing you can do is observe the fish and tank, keep doing water tests and just hope that it was just some freak illness that killed them. It could have well been something to do with the water change, I really don't know.

sorry to hear about your loss.
im also at a loss to what the problem might have been that killed one oscar made another ill and yet has not affected the rest of your stock. personally i would keep a close eye on the remaining fish and watch closely for signs of distress as well as continuing to monitor the water parameters

sorry to hear about your loss..

hope your other ill oscar gets better mate

I rechecked water this morning(Tue)and will do so daily,all is fine at mo, sick fish seems a bit better,very pale not moving but he is moving his fins and tail now. the female he paired off with sometime ago is watching over him and fighting off all that go near.breathing seems fine(light,slow,) I am hoping he will recover now as i did not think he would last a night. my 1st thought was poisoning of some kind,due to water change but all other fish are still fine.

i304.photobucket.com/albums/nn198/luckyl...otos/sickfish003.jpg

Oh dear, he does look sorry for himself. Is he breathing heavily at all?

No very lightly but slow,deep..seems to cough sometimes. but he will not move so this maybe why hes not breathing heavy?? he can move if provoked by other fish.

Could they have been injured by fighting? sometimes fish will bash other fish in the side causing internal injuries that can and sometimes do kill. Had your other 2 oscars paired up, was there any aggression in the tank

never any real fighting just a little mouth showing or small nip. The one thats still alive but sick never fights and only bites me(always backs down) there was no damage on both fish. I condidered this also. It has me very puzzled as hes still the same but has some colour back in body. My bigger problem is I go on holiday in a wks time. i got some clove oil as a last result, but im holding out. Hes a strong fish and was in good condition antill this, so i am hoping.I have kept fish since I was 7yrs and am now 43 so have seen a lot of problems. This was very sudden. I did a 50% water change just incase there was a problem with the last change and cleaned all equipment. as to pairing off sick fish paired off with dead fish at one time(2yrs ago) but then paired with with another female a few wks after but thats 2yrs ago and all was fine since.The 2 females had a little fight a month ago over a rock but i put another rock and again all was ok.

I am stumped on this one. If it was one fish then you could put it down to a weakness/problem in the fish, but with 2 getting ill it points to something tank wide. Best keep a close eye on things and hope it doesnt happen again. Hopefully you have someone to check on your fish while you are away. Helf feeding while you are away

Just to let you know how things ended,as many people put up posts but never tell the outcome, after 10 days treating sick fish there was no improvment. I had to go on holiday for 2wk so helped sick fish along the way to the big fish tank in the sky. All other fish seem to be doing fine and i am none of the wiser as to why,what, the problem was. water conditions where fine on return even after 2wks away.The loss of 2 fish has made life easier. Hoping all is back on track now.

sorry to hear about the loss of your fish.

hope the poroblem is over now.