Lost all fish - what is this?

[Red2143]

For the past 1.5 years I've had a biocube with a clown fish, pj cardinal, tail spot blenny and royal gramma. Nothing has been added to the tank for over 6 months.

All the fish died over the course of a week. I didn't see anything unusual but the last fish was the clown fish and clearly had a problem. The coral is all still doing great.

What disease does this look like?

What could have caused it to hit so hard after all this time? The only change at all was dkh dipped to around 5 but corals werent impacted.

 

[Gumbies R Us]

#fishmedic

 

[Sharkbait19]

That looks like late stage ich to me. Were the fish quarantined? Ich can go unnoticeable for a while before finally getting bad.
All you can do at this point is fallow the tank for 60 days and quarantine all new fish.

 

[Dom]

I'm guessing Brook or Velvet.

 

[vetteguy53081]

For the past 1.5 years I've had a biocube with a clown fish, pj cardinal, tail spot blenny and royal gramma. Nothing has been added to the tank for over 6 months.

All the fish died over the course of a week. I didn't see anything unusual but the last fish was the clown fish and clearly had a problem. The coral is all still doing great.

What disease does this look like?

What could have caused it to hit so hard after all this time? The only change at all was dkh dipped to around 5 but corals werent impacted.

May have begun as brooklynella but fish has a bacterial issue which has led to fin and tail rot and deterioration of skin. Best recourse would be to isolate any remaining fish and treat in separate tank with seachem Kanaplex or neoplex, Do a major water change on display tank and leave it without fish (fallow) for at least 6 weeks.

 

[Jay Hemdal Verified Community Expert]

After-the-fact diagnosis is always tough.

Visually, the clown could have had late stage ich or Brooklynella, followed by a secondary bacterial infection.

Velvet causes rapid breathing and not eating as the first symptoms, at the very end of the infection, you'll see some skin changes.

It was almost assuredly a fish pathogen because your corals and invertebrates were left in good condition.

Your best bet would be to leave the tank fishless for 60 days, and then begin adding new fish, but either quarantine them, or buy pre quarantined fish.