Sudden fish death..

Question
QUESTION: A few days ago i noticed in one of my tanks the white calvus panting at the bottom of the tank, with hardly no movement etc.., a few days b4 that i noticed one everynow and then rubbing against the rock, i checked for white spot but found nothing, i also did all the tests and everything came up normal..
A bit confussed i decided to do a water change and also add a new air bubble curtain in the back for more filtration..

Today i found 3 of the smaller ones dead and the 2 breeders not looking to well, on the bottom, sometimes lying on the side..Looks like i will lose them all, have risen the temp to around 29 and added a little salt.

As mention, all the test came up ok, so im puzzled to why this has happen, i use the same methods and water with the other tanks and they are doing fine..

What might have caused this to happen?, or is it one of those things that cant be answered?

I just wish i knew why or hoped something came up on the nitrate/nitrite/ammonia/ph tests..

Any ideas or thoughts would be appreciated

Cheers

G

ANSWER: Hi George
Did the ammonia and nitrites read 0 ppm, and nitrates were under 20 ppm?  Any amounts  of ammonia and nitrites is toxic to fish, some handle it better then others though.  But, those will also cause the same symptoms you described.

And, is the ph remaining stable, it's not fluctuating around?  A fluctuating ph can cause the fish to scratch or flash.

If those are the readings you were getting, it sounds like it may have been gill flukes.  With gill flukes, you can't see them, but some of the symptoms are the fish lays at the bottom breathing heavy.  Those are usually the "end" symptoms, right before they die.  In the beginning, they'll hang at the top, especially around the filter output areas and scratch on objects in the tank.
But, it seems strange that the others died after you did the water change.  
Were they showing any symptoms at all?

How big of a water change did you do?

How often do you do water changes?

Anything-plants, fish, rocks, etc new added to the tank recently?

Christy



---------- FOLLOW-UP ----------

QUESTION: Hi Christy,

Thanks for the helpfull information, a friend of mine told me today it might be gill flukes, if i knew of this earlier i could have checked there gills after death, but it is a painfull process, seeing your fish die, so i dont think i can handle studying the fish...

I did 20% water changes 3 days in a row

I normally do water changes every 7-10 days, as mentioned, use the same water and use the same methods for all 4 tanks and all the others are fine.

I also have 2 tetras and bristlenoses in the tank and they are doing fine for now, although i did notice a blood spot from there fins..

The only thin i added to the tank was 2 mystery snails, which i swapped from the top tank as they laid eggs..

Thanks for your time and help

regards

George

Answer
Hi George
Let me ask you this, were the 5 fish that died all the same types-the white calvus?  

How long did you have the fish (that died)for?

Do you happen to know if the fish were "wild caught" or were they tank raised?

I ask because a lot of times when you buy fish that are caught from the wild, they'll need to have pretty much the same set up as they had in the wild, meaning the ph should be the same, salinity levels, etc.  And, they're usually going to have parasites as well. But, fish that are bred on farms or tank raised from breeders will be a little more hardier and usually can tolerate a wide range of ph levels, they're not as sensitive to that stuff.

Christy