Fish dying fast

[tcorrell02]

What would cause fish to go from acting fine to dead in less than an hour. Yesterday I lost 2 damsels and everyone else acted fine. This morning about 6:30 I fed the fish and everyone ate and life was normal. Fast forward to 9:45 all is good, everyone seems fat and happy. 10:00 domino dot and oscilarus clown both dead. I am at a loss here

 

[TX_REEF]

will need your water chemistry measurements to help. Also would be good to know the age and size of your tank.

 

[GARRIGA]

Check to ensure there's surface agitation as oxygen levels may have dropped. Usually largest go first or show signs of distress. Examine what was done recently. This is the cause I've run into when suddenly perfectly healthy and eating perished.

 

[vetteguy53081]

What would cause fish to go from acting fine to dead in less than an hour. Yesterday I lost 2 damsels and everyone else acted fine. This morning about 6:30 I fed the fish and everyone ate and life was normal. Fast forward to 9:45 all is good, everyone seems fat and happy. 10:00 domino dot and oscilarus clown both dead. I am at a loss here

In cases like this, its often water quality or disease.
Were fish found dead with mouth open or closed (any pics?)
What is ammonia and nitrate levels and how are you testing?

 

[tcorrell02]

In cases like this, its often water quality or disease.
Were fish found dead with mouth open or closed (any pics?)
What is ammonia and nitrate levels and how are you testing?

Ammonia is 0, Nitrite 0, Ph 8.0, Nitrate 40 tested with API, I know I know, it's what I have on hand. Mouth was closed, no visible wounds or infection like ich or velvet, etc. Tank is 5ish months old, fish have been in for 4ish months. Only thing added in the past few weeks was a couple corals and I changed my lighting from led to t5 and mh.

 

[vetteguy53081]

Ammonia is 0, Nitrite 0, Ph 8.0, Nitrate 40 tested with API, I know I know, it's what I have on hand. Mouth was closed, no visible wounds or infection like ich or velvet, etc. Tank is 5ish months old, fish have been in for 4ish months. Only thing added in the past few weeks was a couple corals and I changed my lighting from led to t5 and mh.

I would highly encourage you to verify water by taking a water sample to a store that does NOT use Api kits and have them test your ammonia and nitrates and compare readings- then you'll know where your levels truly are at

 

[LandLockedJones]

I’m no expert, but this is where my head is going.

What is the tanks water volume?

How long ago did you switch the lights?

I ask because mh and t5 lighting would add more heat to the tank than the leds. So might check temp is still stable if the addition was recent.

Does the water look cloudy? Could be a bacterial bloom reducing oxygen to the system. Which could have been fueled by recent changes in lighting or as stated lack of surface agitation.

Have you done a recent water change? Again, I’m no expert but 40ppm nitrate seems pretty high. I am not sure if api kits can test that range accurately as I have not had one. But if it is that high, may want to do a large water change. 40 seems high to me, but may not actually be in a toxic range.

Do any of the remaining fish show signs of disease? (Do any appear as though they were dusted with powdered sugar? Breathing heavily? Look closely because the only disease I’ve heard of that kills this effectively is marine velvet)

All that being said, I’m sorry to hear you are having trouble right now. I hope you are able to figure it out and save the rest of the tank.

 

[Jay Hemdal Verified Community Expert]

What would cause fish to go from acting fine to dead in less than an hour. Yesterday I lost 2 damsels and everyone else acted fine. This morning about 6:30 I fed the fish and everyone ate and life was normal. Fast forward to 9:45 all is good, everyone seems fat and happy. 10:00 domino dot and oscilarus clown both dead. I am at a loss here

Are there corals and other invertebrates in the same tank? If so, and they are thriving, and if the tank has good aeration, you can 100% rule out simple water quality problems.

The most common cause for fish dying “suddenly” is marine velvet, Amyloodinium. The symptoms come on so fast that they are easily missed until the fish start dying.

 

[Not_Erick]

I know this may seem obvious but have you changed your water after the deaths?

 

[MnFish1]

What would cause fish to go from acting fine to dead in less than an hour. Yesterday I lost 2 damsels and everyone else acted fine. This morning about 6:30 I fed the fish and everyone ate and life was normal. Fast forward to 9:45 all is good, everyone seems fat and happy. 10:00 domino dot and oscilarus clown both dead. I am at a loss here

Curious - did all the fish die - or just some - and what was the last addition aside from coral. I don't have any reason to doubt the API tests - they are about what's expected in a tank 5 months old. Additionally, the issue with API tests is usually a falsely high ammonia - as compared to a low ammonia (0).

With regards to nitrate - I don't remember the upper range, however it's not something that would cause sudden toxicity. one thing you can do would be to depending on the high range is to dilute the sample with fresh (not from the tank) saltwater and then multiply any value you get by 2. That said - I think 40 is within the parameters of the API nitrate test.

There is nothing I can think of that would change so quickly such that a fish is normal one minute and 15 minutes later 2 are dead. Especially if others survived, and your corals, etc look fine except as @Jay Hemdal mentioned velvet - but this seems even quick for this.

So if you can give a little more history that would be great. Any chance your food was contaminated with something?