Mass death of long term fish

[David Middleton]

Today I found that at least 6 of my fish had died without showing earlier evidence of distress. I have lost all 3 Clown loaches which I have had for more than 5 years and both my Corydoras catfish plus at least one emperor tetra.
They were in my 200liter tank with other fish (some of which look a little listless), Tank is heavily planted and filtered by a JBL Cristal filter . Temperature normally 25-26C. I have run a test on water and noted a considerable rise in Ammonia. I therefore think this is the obvious cause. But WHY has this happened after years of stability? I have now just changed out 1/3 of the Water (I normally change out 10% twice a week and 20% once a week). I have also added some Interpet Ammonia remover and now the water seems normal again.

 

[gwand]

Did the ammonia spike kill the fish or did the large amount of dead fish cause the ammonia spike? How long do you estimate the fish have been dead before discovering them?

 

[GaryE]

I see 200 ltrs as a suspect. It's an unfortunate thing most longer term fishkeepers here have seen, but some fish sadly grow into their deaths. Clown loaches grow very large, and while a too small for them tank like that can slow their growth, they reach a point where that becomes untenable.
One dies, ammonia spikes, the other stressed by tank size individuals succumb, and you get the dreaded established fish die off.

It isn't an uncommon event with clown loaches, plecos and other bruisers that are sold to us almost as fry, and that outgrow their chances unless we buy very large tanks for them. I wouldn't keep clown loaches in my 2 metre tank, as adults are too large. Guess how I learned that?

We can commiserate, but it's a mistake that takes a few years to become evident.

 

[David Middleton]

I see 200 ltrs as a suspect. It's an unfortunate thing most longer term fishkeepers here have seen, but some fish sadly grow into their deaths. Clown loaches grow very large, and while a too small for them tank like that can slow their growth, they reach a point where that becomes untenable.
One dies, ammonia spikes, the other stressed by tank size individuals succumb, and you get the dreaded established fish die off.

It isn't an uncommon event with clown loaches, plecos and other bruisers that are sold to us almost as fry, and that outgrow their chances unless we buy very large tanks for them. I wouldn't keep clown loaches in my 2 metre tank, as adults are too large. Guess how I learned that?

We can commiserate, but it's a mistake that takes a few years to become evident.

WOW! This is very interesting and may well be the exact cause. All 3 of the clowns were ok yesterday during the day and as you say, I had owned them from 1 inch long to their eventual 4-1/2 - 5 inch size. Scales were being cast when I retrieved the dead fish and so this may have caused the spike. Hopefully my other fish will survive. We will see.

 

[GaryE]

I wish I weren't talking from experience here, but let me tell you about my old clown loaches...

I would accelerate water changes for a couple of weeks - 3 five inch loaches are quite an ammonia punch, even short term.

It sounds like you were doing everything right otherwise.

 

[David Middleton]

I wish I weren't talking from experience here, but let me tell you about my old clown loaches...

I would accelerate water changes for a couple of weeks - 3 five inch loaches are quite an ammonia punch, even short term.

It sounds like you were doing everything right otherwise.

Thanks;
I will do a daily 10% change for a couple of weeks.

 

[seangee]

Thanks;
I will do a daily 10% change for a couple of weeks.

I would go bigger on the water changes, at least for the first week or so. 10% out means 90% left in the tank.

 

[David Middleton]

I would go bigger on the water changes, at least for the first week or so. 10% out means 90% left in the tank.

Noted and I will defer to you on this. Thanks.