Sudden death of angelfish

[dandries]

An angelfish I have had about three weeks died last night. Yesterday he was fine and today he was hovering in one of the plants dead... as if he died suddenly. I cleaned the tank yesterday and water levels were fine. Ph 7.2, ammonia 0 and nitrites 0. Nitrates were around 40 but I did a water change and today they are 0.

I did how to change filters because it stopped working but I swapped it with one I had going in another tank so it had bacteria in it plus I used some of the media from original filter.

The other two angelfish appear normal. I don't see anything wrong with it and I attached a picture.

Any clues?

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[MICEY]

how big is this angel small ones die all the time for no reason
if there larger the other 2 might be a pair and he got killed in a fight

 

[dandries]

He is small. There is a larger one, but he only has 1 eye, and not a threat.

The new one is this size.

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