Mass fish death overnight - except clowns

[keizo]

Hi everyone,

It pains to me type this out but wanted to seek counsel for what my next steps could be to protect my remaining livestock and to confirm my suspicions on what may have caused this issue.

Seemingly overnight, between the hours of 11PM and 8AM this morning, all but my 5 clownfish have died or presumed dead (presumed dead because I've already netted out 3 dead fish, out of a possible 4 additional fish that I have not yet been able to see and who regularly come out during the morning hours).

My water parameters are the following:
-Nitrate: 0.0 (Hanna)
-Phosphate: 0.0 (Hanna)
(My nitrate and phosphate levels being at 0 have been a separate concern of mine that started at the same time a small cyano outbreak occurred around 2 weeks ago).
-Salinity: 1.027 (teeters between 1.026 and 1.027) (Milwaukee)
-Ammonia (Red Sea visual checker = 0.2?
-Temperature: According to my Neptune Apex, it never fluctuated outside the 78F zone for the last 9 hours.
-Tank age: over 5 months old
-Tank size: 100 gal DT; 145 gal DT+Sump

• My biggest hypothesis is that there was a big enough ammonia spike (assuming the Red Sea visual checker is accurate) that caused these fish to die overnight. I did add 3 small fish two days before this issue occurred and acquired them from a vendor that puts the fish through a quarantine process before handing them to me. My suspicion here is perhaps that these 3 fish added more bioload that my nitrifying bacteria was not enough to transform into nitrate. I'm not sure how common this is as a cause for massive fish death.
• There have been no signs of disease on any of the fish before this occurred, and I doubt disease would take every one of the fish other than the clownfish out this quickly. All fish have been acting normal up until the evening last night, where I did notice my usually very active Goldhead Goby was hiding in his cave.
• Can rule out fish aggression... I doubt the clownfish decided to combine forces to take every other tankmate out
• No power outages

Any ideas on what could have caused this?
Marked as an emergency in case someone could help me confirm some additional steps that may be helpful in potentially rescuing my remaining clowns. At the moment, I'm not really sure what to do other than a big water change.

 

[SlugSnorter]

assuming the test is right, thats a possibility. Do you have any inverts or coral? if so, have they been affected?

 

[keizo]

I do have three shrimp (skunk cleaner and 2 peppermint) - they're all a live and okay now.
I also have 1 turbo and 7 trochus - can't really account for all the trochus but the turbo is alive and some of the trochus are alive.
I also have corals:
LPS = frogspawn, scoly, acanthophyllia and alveopora
Softies = GSP, leather, one zoa colony

While I'm typing this I could add a few more details I've missed:
-pH didn't swing drastically - between 7.8 and 7.97 over the past 12 hours
-I have been dosing nitrates because my nitrate levels have been so low - using B-ionic Nitrates to try to get Nitrate levels to about 1ppm
-I have also been using Macrobacter 7 in a slow and steady attempt to get these bacteria to outcompete the cyano outbreak I mentioned above
-I regularly dose Red Sea Coral AB+
-I regularly dose phytoplankton
-I got a golf ball size shipment from Algae Barn for Chaeto yesterday, which I pre-washed in saltwater before adding directly into my pre-existing refugium (most of which has been comprised of ulva and ogo)

 

[Garf]

Nah, Ammonia has got to be a lot higher than that to kill fish in a normal tank, even less likely with a pH of 8 ish. Fish disease is likely from your recent additions.

 

[keizo]

I'm not terribly well-versed in the library of fish diseases out there, but is there a fish disease that could spread from (presumably) 1 fish to 7 other fish and kill them in <48 hours?

I'm assuming that disease would also have to be somewhat less effective against killing my 5 clownfish - who are all seemingly fine at the moment.

@Jay Hemdal leaning on your expertise here if you have any insight

 

[Spare time]

I doubt it was disease since that would seem odd that they would have 0 symptoms and then die all at once at night. If they all died at night, it may have been an oxygen issue.

 

[Christian0505]

I'm not terribly well-versed in the library of fish diseases out there, but is there a fish disease that could spread from (presumably) 1 fish to 7 other fish and kill them in <48 hours?

I'm assuming that disease would also have to be somewhat less effective against killing my 5 clownfish - who are all seemingly fine at the moment.

@Jay Hemdal leaning on your expertise here if you have any insight

Well yes, there is velvet, which could kill your fish extremely quick, spread like a wild fire, but clown fish are less sensitive to. However you would notice it on the fish/dead fish as they would be covered in white powder.

 

[keizo]

Just to be clear - no VISIBLE signs of disease on the fish that have passed that I was able to see.

Not discounting that it could be possible, but none of the fish have displayed any signs of the major diseases that I'm familiar with (brook, velvet, ich). None of them have shown any visible signs of odd behavior either (no heavy breathing or lying on their side, etc.)

The extent that I've seen in hindsight is that the previously-alive fish seemed to have hidden in their usual rockwork a bit earlier in the evening.

 

[C4ctus99]

What all fish did you have in the display tank?

+1 on maybe looking into oxygen issues

 

[keizo]

-yellow tang (biota, baby size)
-exquisite fairy wrasse
-goldhead goby
-foxface rabbitfish
-royal gramma
-Midas blenny
^ these are all the ones that perished
My yellow coris wrasse is still alive along with my clowns (just saw him burrow)

 

[blue-thumb]

So sorry! Ammonia levels rise when there is something dead in your tank. It may not be what caused the problem. I had this problem on one occasion when my skimmer failed. The skimmer adds oxygen to the water as well as regulating PH. The fish could have died from lack oxygen. The smaller fish die first. The second occasion, I had just bleached my freshwater makeup containers. A friend used those containers to refill the tank before rinsing them. He felt really bad. My fault!

 

[Jay Hemdal]

+1 on it not being an ammonia issue.

I was leaning towards Amyloodinium (but that is ruled out by tonight if the wrasse and clowns are still asymptomatic) or, a transient dissolved oxygen deficiency.

At night, algae goes into reverse phase photosynthesis and takes up oxygen and produces CO2. If the tank does not have good aeration, or if the aeration is disabled temporarily the fish suffer, and the percentage dying depends the level of gas exchange issues and the species involved.

Does your tank have a protein skimmer on it? If not, what mechanism do you have to ensure proper gas exchange?

Jay

 

[keizo]

Thanks for weighing in here @Jay Hemdal - always appreciate your input.

The only gas exchange that occurs is with my Vortech MP60s and protein skimmer. I incidentally did turn off my protein skimmer the past two nights because I have been dosing Macrobacter 7 at night (instructions indicate I should turn off my skimmer) and because my nitrate/phosphate levels bottoming out (i.e. trying to raise my nutrient levels to be above 0 by reducing mechanical filtration).

I have kept the skimmer running and can check back in tomorrow with updates (fingers crossed and hoping to share that the remaining wrasse and clowns are still alive and well).

In addition to all this, I'll summarize some stuff here as well as answers in the hopes that anyone who has experienced anything at this scale like I have could read this and learn.

(1) I have now since put less weight on my initial hypothesis that perhaps Ammonia was the reason behind the massive fish deaths. I figured that it would have likely impacted the clowns as well as my surviving yellow corris wrasse. The level is at ~0.2ppm and it isn't clear whether this was the level of ammonia before the fish have died overnight, or after they died (when I took the reading).

(2) I do not believe the cause of the deaths are attributable to a virulent disease. The timeframe seems overly aggressive for anything to have spread to the aforementioned fish in <48 hours while showing no visible, external signs of disease, while 6 other fish in the same tank have been fine (5 clowns, 1 yellow corris wrasse). This is harder for me to stand behind confidently because I simply cannot validate without external signs of disease and I am not a fish disease expert.

(3) I'm not sure if it's a voltage leak of any kind. I ran a quick copper HR test with Hanna and it shows 0.00. Plus, all my inverts look healthy (3 shrimp total; skunk and 2 peppermint. In addition to all my corals that seem to be doing fine).

(4) The primary suspect now is oxygenation issues. Could it have been due to the unfortunate combination of additional macroalgae I've added yesterday (golf-ball sized chaeto) + turning off my protein skimmer (because I was dosing Macrobacter 7 + I was intentionally reducing my mechanical filtration to get my nitrate/phos levels to be above 0.00).

 

[MnFish1]

To me this suggests a disease to which the clownfish were (somehow) immune - can you say more about when and what was added last? Second - The ammonia does not seem to be an issue that would have 'Caused' this - but - I would continue to check it. - since you have 4 dead unfound fish. You may (because of that) - want to add some nitrifies (Fritz) - etc. So sorry this happened. I also doubt 'voltage' - should have killed everything. The only reason I'm leaning towards a disease - is that I don't know whether the fish were QT'd - etc. Additionally it could be a soap, or toxin (I'm not a big believer in this - ie a spray of windex etc - but I would consider a chemical issue - that the clowns were less susceptible to.

 

[MnFish1]

Could it have been due to the unfortunate combination of additional macroalgae I've added yesterday (golf-ball sized chaeto) + turning off my protein skimmer (because I was dosing Macrobacter 7 + I was intentionally reducing my mechanical filtration to get my nitrate/phos levels to be above 0.00).

Whenever I look at these things - (and I didn't see your post) above - look at things that happened recently - a new fish, etc etc. This could be oxygen related - something on the algae (doubt) The microbacter 7 - causing low O2, would rise the cause level

 

[keizo]

Yeah, happy to elaborate on the fish disease front.

Again, I myself am unable to 150% validate or rule it out, but I have my skepticism for the following reasons.
I picked up the three fish from a vendor two days ago (Wednesday), which I had placed an order for about a month back. The vendor puts the fish through a quarantine methodology, which includes freshwater dip dosed with Praziquuentel for 3-5 minutes, treatment with Chelated Copper Sulfate and Nitrofurazone (copper being run at 2.5-2.8ppm). This is done with a minimum of 14 days (consecutive days protocol, i.e. fish has to be clean and not show signs of infection at any point during those 14 days). Again, I am not there every day to inspect this process, so of course I have a blind spot here and have to take the vendor's word for their process. I examined each fish visually at the vendor prior to accepting them, as they showed no visual signs of disease. Upon being put into the DT, they were all displaying very good personalities and were all eating the frozen foods I usually provide to the other tank inhabitants.

I have since visually inspected the dead fish -- all of which were now identified and taken out of the DT -- none of which showed any visual, or external signs of the obvious symptoms of the only two diseases I could detect with my naked eye: velvet, ich, brook.

 

[Christian0505]

To me low oxygen is the first thing that comes up now. You try to increase bacteria, which consume oxygen, you turned of the skimmer, which lowers the oxygen even further and increased the fish population increasing the demand..

Do you by any chance dose any carbon related things such as NOPOX?

 

[keizo]

Thanks for weighing in @Christian0505 - I do not dose NOPOX.

Here are all the additives outside of basic fish nutrition that I add/have begun adding:
(1) Red Sea Reef Energy AB+
(2) MacroBacter7 (started dosing this since Tuesday of this week)
(3) B-Ionic Nitrate (started dosing this since Wednesday of this week)
(4) Zeobak, Zeofood Plus, Zeostart 3

Here are all the things that were different this week as well:
(1) Chaetomorpha (golf-sized ball added Wednesday)
(2) 3 small (2-3") fish (Royal Gramma, Midas Blenny, Exquisite Fairy Wrasse)
(3) Protein skimmer turned off at night, following instructions on MacroBacter7
(4) Phosphate and Nitrates bottomed out this week (0.00 on both)
(5) Cyano outbreak has slowed down since last week, almost corresponding to the timing of my nutrients bottoming out

Business as usual
(1) Filter socks (mesh and fine) changed every 3 days
(2) Stocked Refugium (ogo + ulva) (12 hour photo period between 9pm and 9am)
(3) Activated carbon
(4) Weekly water changes (have never missed a weekly water change since the tank was set up) - 10% volume every Saturday

 

[MnFish1]

he vendor puts the fish through a quarantine methodology, which includes freshwater dip dosed with Praziquuentel for 3-5 minutes, treatment with Chelated Copper Sulfate and Nitrofurazone (copper being run at 2.5-2.8ppm). This is done with a minimum of 14 days (consecutive days protocol,

thanks I don't want to criticize your fish store - but - this is not acceptable. A 3-5 minute dip of praziquantel is nothing. And 14 days is too short

 

[Ben.QLD2]

Do you have any Sea cucumbers/apples, nudibranchs or similar?

I had a full tank crash about 12 years ago after a cucumber was shredded in a wavemaker. They release a potent toxin from their tissues.

The only survivors were a pair of tomato clowns.