Emperor Angelfish died overnight

[Rammeh]

Hey, I wondered if anyone would help shed some light but I have a Fish Only 55 Gallon setup, with a Fluval 405 and five large pieces of live rock. Its been running now for about 2 months.
In the tank there are two Black & White Ocellaris Clownfish, A long nosed Hawkfish, a brown Hawkfish and a Valentini Puffer and up until this morning a juvenile Emporer Angelfish. Sadly this morning he was dead drapped across a rock! Last night he was absolutely fine, he was eating fine, breathing normally and swimming around as normal. This morning dead.

I did an ammonia the night before and it read 0.25.
Really anoying as really liked him!

 

[Swimzebras]

Why was there any ammonia!? That seems to me like it's the culprit

 

[Rammeh]

Im not sure... would there not have been signs if that was the case?

 

[Swimzebras]

I think it varies, there's ammonia burns but I believe that's from prolonged exposure to high levels. I'm not sure otherwise. Is it possible that you caught the beginning of a spike?

 

[Rammeh]

Perhaps I'll do another test tonight then.....

 

[Swimzebras]

Good idea. If there is still some ammonia and/or nitrates do a PWC

 

[Rammeh]

oh I did do about 25% on saturday... is that likely to make a difference?

 

[Swimzebras]

Yes, but if you still have any ammonia or nitrite you would probably be wise to do another. Sorry for the much delayed response