Can anyone explain what happened here

[Magzire]

During last August I bought 2 new colored fancy goldfish and added them to the pond. When autumn arrived i wanted to bring in all the small fish inside to the aquarium.
I could only find one of the new goldfish, so brought him in along with the others and left the big fish in the pond. After a couple of days he started breathing rapidly and not eating, then not moving at all. Few days later he died, but he was the only fish that past away in the aquarium.

Last week after months of not seeing his brother i finally found him by accident, he was still the same size and didn't grow at all during those months but looked healthy.
The exact same thing happened to him, I'm puzzled to why this only happened to these two fish while the others a thriving in the aquarium, they grown so fast and all healthy.

 

[Lisak1]

So you found the second fish and brought him inside and then he died? Hmmm... that's a puzzle, especially since he seemed fine when you caught him. Do you test your aquarium water? How many fish are in the tank? How big is it? Just trying to get the whole picture here -

 

[Magzire]

By the way I did acclimate them

So you found the second fish and brought him inside and then he died? Hmmm... that's a puzzle, especially since he seemed fine when you caught him. Do you test your aquarium water? How many fish are in the tank? How big is it? Just trying to get the whole picture here -

I have a 106 fluval with a 400l airstone for a 70l tank. The filter is cycled with 50% weekly changes. Far as i know the water is perfect, the other fish have grown so fast with no issues.

 

[Magzire]

Maybe it a pH thing? Last time i measure the pond it was in the low 7. Tank is around 8

I did acclimate him for a whole day, he was eating the next day. Then added him to the tank, 3 days later the exact same happened with the other fish.

 

[Lisak1]

Hmmm... strange indeed. pH might make sense, but I didn't think goldfish were all that picky about pH. Hopefully someone else with more aquarium experience will chime in here. @MitchM - any ideas?

 

[Dave 54]

Maybe it a pH thing? Last time i measure the pond it was in the low 7. Tank is around 8

I did acclimate him for a whole day, he was eating the next day. Then added him to the tank, 3 days later the exact same happened with the other fish.

@Magzire your mistake is thinking it only takes 24 hours to acclimatise them (it can take days) you should have raised the temperature a degree at a time over days but I suspect your first mistake was in not Quarantining your fish in the first place.prior to them going into your pond .
I suspect hey may have picked up something in the pond that your larger fish have learned to cope with the smaller ones not ,

Dave 54

 

[Faebinder]

My experience.

Cold to Hot..... big problem... more than 10 degrees is death. You have to do it slowly. Stretch over 3 days if needed. The increase in temperature will increase the requirement for oxygen and the metabolism may not catch up in time.

Hot to Cold... Less of a problem. Still show be done incrementally if possible. The drop of temperature drops the metabolism so less oxygen is needed.

 

[Magzire]

thanks for your inputs