What causes a fish to die when the other tank inhabitants are fine?

[djryan2000]

I woke up today to one of my clownfish unexpectedly dead. His body was pinned to the back of one of my powerheads. He even ate when I fed the tank before going to work.

Alk - 8.9 dkH
Magnesium - 1380 ppm
Calcium 420 ppm
Phosphate - undetectable but using salifert
Nitrate - 10 ppm
Salinity 1.026
pH - 8.15
Ammonia - 0
Nitrite - 0

Is it likely he got caught behind the powerhead despite my fish / nem guard?[emoji21]

 

[Tcook]

How old was the fish?

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[djryan2000]

How old was the fish?

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I don't think very old. I purchased him from my LFS only few months ago.


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[CrazeUK]

Often, when fish die, they'll get caught in the water flow. So being trapped wouldn't necessarily be the cause of the death.

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[djryan2000]

Update - the day of posting this I ended up picking up a different clown to put in the tank to please the Mrs. in my household considering everyone else in the tank was happy. My LFS had a bunch in an anemone tank for a while so I figured it was worth the risk of not QTing and they keep the same salinity / water parameters as me.

Today, I came home to finding his head caught in the powerhead, after he was eating and swimming normally 10 hours before. Again, all my SPS corals are all happy and open.

The only change I can think of that I made before this was adding a anemone / fish guard to the powerhead that I found both fish caught behind. I have a hard time imagining this being the cause of death as it's meant to protect them, but it's the only variable I can think of. I'm at a loss as to why they've died under my care. I have no clue what I'm doing wrong, and it's so unbelievably frustrating.

 

[Timfish]

Often, when fish die, they'll get caught in the water flow. So being trapped wouldn't necessarily be the cause of the death.

I'll second this. It's frustrating but most of the time we won't know why a fish died. You shouldn't take this as something you're doing wrong, especially with a new fish as you have no idea of it's history, what stresses it may have had that may have weakened it. Lot's of aquarists have done very similar setups and not had a problem, healthy fish will instictively swim against a current. If you feel like you need to take additional steps home improvement stores will have a heavy black course screening used for keeping debris out of rain gutters you could fashion into an additional guard with tie wraps/zip ties.