What did i do wrong?

[YellowFinsReef]

Recently, i was trying to move a pair of bangaii cardinals to another tank to focus on their breeding (3x breeding unsuccessful).

I used a container to scoop the male to put it into the specimen container for acclimation and took my eyes off of it for a minute while i tried to catch his mate.

When i took a glance at it after catching his mate, i noticed that he was twitching sideways with his jaw wide open while struggling to swim. It died 5 minutes later.

Any speculations on the above issue?

 

[HotRocks]

Recently, i was trying to move a pair of bangaii cardinals to another tank to focus on their breeding (3x breeding unsuccessful).

I used a container to scoop the male to put it into the specimen container for acclimation and took my eyes off of it for a minute while i tried to catch his mate.

When i took a glance at it after catching his mate, i noticed that he was twitching sideways with his jaw wide open while struggling to swim. It died 5 minutes later.

Any speculations on the above issue?

Could you have injured the fish when catching?

 

[YellowFinsReef]

I thought of that too, but there was no possible way the fish could have been injured. It wasn't handled improperly or anything and this is quite the first time I've seen this during a transfer.