Tank crash...2.0

[Jay Hemdal Verified Community Expert]

Jay
Ok thanks. Thought the CUC couldn't carry over anything like Brook or Velvet but sounds like that isn't fully true. In any event tank did get cleaned with bleach x2 and then fallow since Jan 2026 so it should be good. All corals and things living in the water column did not survive. Now this far out do you think I am ok?

As for adding new additions to QT reseting the previous fish duh I should have thought of that...if so would have moved fish earlier. However I did move my maroon clown and stripies before adding todays new fish and they as said have been in QT since Jan at 2.00-2.24 ppm Coppersafe so should be ok in DT. Rest of fish will reset as new addition was today and previous one 3/4 and 2/18 as said. What do you recommend against flukes? Can I do Prazipro the the DT or keep it to the QT or use a 10gal pre-transfer tank from QT to DT? What in my particular set up would you suggest? Thanks again...you're a great source of info!

I would try handling any flukes in the QT. While you *can* treat your DT for flukes with prazipro, it isn't the best option - more expensive, harder to eliminate fluke eggs and there is always some risk to the invertebrates.

Here is a write-up I did on dosing prazi:

https://www.reef2reef.com/threads/dosing-praziquantel-pzq.1105700/

 

[Louis Z]

As for CUC I do the tank transfer method . It’s a pain , but 2 or 3 x 10gal tanks set up at the same time with same water to keep changes to a min. I am trying to leave behind any nasty parasite behind . Most stores have fish in with the CUC or they are plumbed into the same filter system . They are constantly getting new fish in so their systems are always suspect . The parasites don’t necessarily have to be attached to the CUC . They can be in the water from which they came in . That is what I am trying to mainly eliminate . I have a final tank set up with macro algae, sand , sponge filter and light to house them for the final finishing stage . . In the initial tanks I have placed limestone tile that I got from Box stores that were broken and they were going to discard . I previously put those in sump or main tank to grow a healthy amount of film algae to place in the initial CUC tanks . After they have cleaned the surfaces , I clean and dry the tile and replace in my main system . I buy CUC a couple months out of the year so I don’t have to do this tedious routine all the time . I learned a lesson because I had put store bought grocery store oyster that are shipped dry in cold and then put on ice . Thought for sure that nothing would survive on the shell but it did . Nasty black Cyanobacteria that was toxic to fish and GHA . It killed my GHA (wohoo) but also made my fish ill but did not kill them . Used chemiclean and I did water change before and after chemiclean with a lot of new carbon to absorb any toxin of the cyano . Yes my method is a pain to me but I have had many new fish and CUC additions to the DT without further incidents .

 

[Pandaexpress]

This is horrible, so sorry for your loss… so scary this kind of thing could happen, I have to use medicated quarantine in the future

 

[mdrobc13]

I would try handling any flukes in the QT. While you *can* treat your DT for flukes with prazipro, it isn't the best option - more expensive, harder to eliminate fluke eggs and there is always some risk to the invertebrates.

Here is a write-up I did on dosing prazi:

https://www.reef2reef.com/threads/dosing-praziquantel-pzq.1105700/

Jay...ok thanks. Biggest question I would have is whether after 3 mos in my QT would there be any flukes left in those three remaining fish? Or the DT? Fish in the DT have been at 2.0 copper or above and eating fine and healthy. No more signs of illness. I did even give them a few doses of Prazi initally the first few days. But not like your treatment. My DT as said as been fallow since Jan so would there be eggs? Also can I treat with Prazi IF i have coppersafe in the QT at the same time?

Also NO fish in QT has gotten sick/ill or shown signs of infection.. Lost a very tiny Hippo at shipment...less than 1.5" but his brother survived and eating nicely. And lost a small juve Angularis that was also less than 2" that wouldnt eat on arrival. But remained for fish in DT have thrived and survived and doing ok. Just added my small Sohal into QT and he's doing ok with the other fish too. All eating and no flashing or powerhead surfing. Sorry glass is a bit dirty..:)

I also just picked up some Metroplex, Kanaplex, and Focus too. Someone suggested getting Ruby Rally to have on hand in future but never used it. Thoughts?

 

[Jungle Blue]

+1 on Petco wipeouts.
I went cheap on a school of chromis to cherry my collection and surely enough, that was the batch that took down 90%.
Found a nsLFS I liked and stuck to them for all my fish now. So far so good.
Wishing well for your reset & comeback

omg +1 on specifically chromis batch..

 

[Jay Hemdal Verified Community Expert]

Jay...ok thanks. Biggest question I would have is whether after 3 mos in my QT would there be any flukes left in those three remaining fish? Or the DT? Fish in the DT have been at 2.0 copper or above and eating fine and healthy. No more signs of illness. I did even give them a few doses of Prazi initally the first few days. But not like your treatment. My DT as said as been fallow since Jan so would there be eggs? Also can I treat with Prazi IF i have coppersafe in the QT at the same time?

Also NO fish in QT has gotten sick/ill or shown signs of infection.. Lost a very tiny Hippo at shipment...less than 1.5" but his brother survived and eating nicely. And lost a small juve Angularis that was also less than 2" that wouldnt eat on arrival. But remained for fish in DT have thrived and survived and doing ok. Just added my small Sohal into QT and he's doing ok with the other fish too. All eating and no flashing or powerhead surfing. Sorry glass is a bit dirty..:)

I also just picked up some Metroplex, Kanaplex, and Focus too. Someone suggested getting Ruby Rally to have on hand in future but never used it. Thoughts?

The general rule of thumb is if a tank is held fishless for 30 days, any larval flukes or fluke eggs will have died out due to lack of a host.

In cases where there are still fish in the tank, even if they are not showing symptoms of flukes, they could still be harboring a sub-acute infection. This isn't super common, but it can happpen.

 

[Louis Z]

On the flip side , I don’t try green chromis anymore .
Each time in QT they have developed the sores showing signs of Uronema . Maybe I was just unlucky twice . One from petco and one from another LFS. Uronema showed up from another LFS on some cardinals . So whether it’s a LFS or petco . I QT and treat as I go and I do TTM .
I do buy from petco . BUT they go thru QT/ TTM / TX !!!! . Just bought 3 lantern bass in succession from Petco . Waiting for each one to come in and each one went thru QT/ TTM /TX with only one showing flukes . Dipped in FW for about a minute and no more scratching for a month. Repeated the dip and another 2weeks of observation . Cleared for release in DT .
It is the process of minimizing the risk of a full blown outbreak in the DT . It is far easier to QT/TTM /prophylaxis /HT than it is to have a DT catastrophe . PATIENCE . I ask myself “HAS the fish /invert/coral/ macroalgae earned the right to be in my DT ? “ . When I have not patiently done this, I was bit in the butt .

 

[mdrobc13]

The general rule of thumb is if a tank is held fishless for 30 days, any larval flukes or fluke eggs will have died out due to lack of a host.

In cases where there are still fish in the tank, even if they are not showing symptoms of flukes, they could still be harboring a sub-acute infection. This isn't super common, but it can happpen.

Okay Jay thanks. Yes the main tank was fallow and fishless since 14 Jan 26 and the first CUC was added around 6 Mar 26 and I just restocked with the last two fish rescued from DT back in late Dec 2025 my maroon clown and 2 Australian Stripies who survived and have been in QT since around New Year even when captured. They were added first and doing ok. Just added my elbi mimic tang on Sat afternoon to DT and he also is doing okay. So I think from a fluke standpoint and most others things the DT is clean now.

Question now is whether to treat with Prazi Pro the current DT inhabitants before transfer to DT or not. I've had them in there now since 3/5 and 2/18 respectively but did add new fish to the DT last Friday 3/20 and 3/21 so as you noted any previous DT countdown clocks should restart with the introduction of new unknown fish. So am thinking at least another 7-14 days now in DT and coppersafe is due. But would you do prazi pro too? I did freshwater dip the three new fish going back into the DT for 3-5 mins before adding and they did okay...didn't like it that much tho! LOL

 

[Jay Hemdal Verified Community Expert]

Okay Jay thanks. Yes the main tank was fallow and fishless since 14 Jan 26 and the first CUC was added around 6 Mar 26 and I just restocked with the last two fish rescued from DT back in late Dec 2025 my maroon clown and 2 Australian Stripies who survived and have been in QT since around New Year even when captured. They were added first and doing ok. Just added my elbi mimic tang on Sat afternoon to DT and he also is doing okay. So I think from a fluke standpoint and most others things the DT is clean now.

Question now is whether to treat with Prazi Pro the current DT inhabitants before transfer to DT or not. I've had them in there now since 3/5 and 2/18 respectively but did add new fish to the DT last Friday 3/20 and 3/21 so as you noted any previous DT countdown clocks should restart with the introduction of new unknown fish. So am thinking at least another 7-14 days now in DT and coppersafe is due. But would you do prazi pro too? I did freshwater dip the three new fish going back into the DT for 3-5 mins before adding and they did okay...didn't like it that much tho! LOL

I would give those fish another round of prazi. A FW dip won't tell you much - only one species of the 4 common fluke types are large enough to see in dip water, the other 3 require a microscope to see them.

 

[mdrobc13]

I would give those fish another round of prazi. A FW dip won't tell you much - only one species of the 4 common fluke types are large enough to see in dip water, the other 3 require a microscope to see them.

Copy that. Well sad to say I think whatever this is is NOT fully gone from my DT. I just lost my Gold Rim Tang after 30+ days QT and only 2.5 weeks in the restarted DT. At first thought it was due to abuse from the Sohal Tang that I QT's him with (abeit with a divider between them) and they 1st week or so they seemed to get along with some mild-mod aggression from the Sohal but nothing major I could see....then saw him with spotted appearance Wed night late and was okay and eating Thur and DOA Fri AM! Now Sohal is wavemaker surfiing in my Nero 7 on either side almost 80% of the time for the last 24hrs! Just caught him and did a 5 min fresh water dip but couldnt seem much with my eyes and reading glasses but now have him in a 2 part Blue lIne Lock QT dip/bath (15 mins part A and 20-30 mins part B) and back to QT he goes. Will catch remaining Purple, Yellow, hippo and Dejardi and Tonami tangs over next 24hrs and do the same I think is best now as the all did ok in QT for 30 days before DT. So far they show no signs but at this point I don't trust the DT system. Agree or am I being paranoid? I wonder could the remaining fish that survived the first episode the two Australian Stripies and my large maroon clown be carriers or something as they made it thru the 1st crash plus QT since Dec thru end of March and are in the DT now doing ok....so far.

As for DT...I think best option is to drain the whole thing. Pull the rocks. Transplant the few coral pieces and inverts I have into my 10 gallon tanks (have 2 empty ones) but how do I treat them as they are in a "wet" system? DT should I just reset it all AGAIN after bleaching it...but this time removing ALL rocks and Sand and just sterilizing the whole thing? Basically new system clean??? Am frustrated as let it sit fallow from Jan thru end of March and still this has happened. Makes you want to quit the hobby man! But appreciate all assistance and antidotes.

 

[winxp_man]

What you’re describing, sounds like, and could be velvet. Flukes will not kill that fast. If I’m reading your post correctly your gold rim died pretty fast. I do not know of flukes killing that fast.

Were the fish flashing? Or just riding the current for oxygen?

With flukes Fish can become lethargic, swim near the water surface, develop clamped fins, hide in the corner of the aquarium or behind rocks, lose appetite, shake the head, flash, or scratch. They may exhibit yawning, cloudy eyes.

One extra thing to look for is swollen gills.

But to got from eating one day to dead the next it would take a crazy amount of flukes and at one point you would see the issue with the fish way before it dies.

 

[slingfox]

Sorry to hear about the recent losses. This situation sounds very frustrating! Since the DT ran fallow for so long it seems unlikely that the DT was the issue. It seems more likely that the fish were continuing to harbor some sort of fish disease. Copper unfortunately only addresses some fish disease. The diseases copper does not address may be what did the Gold Rim Tang in.

 

[Jay Hemdal Verified Community Expert]

Copy that. Well sad to say I think whatever this is is NOT fully gone from my DT. I just lost my Gold Rim Tang after 30+ days QT and only 2.5 weeks in the restarted DT. At first thought it was due to abuse from the Sohal Tang that I QT's him with (abeit with a divider between them) and they 1st week or so they seemed to get along with some mild-mod aggression from the Sohal but nothing major I could see....then saw him with spotted appearance Wed night late and was okay and eating Thur and DOA Fri AM! Now Sohal is wavemaker surfiing in my Nero 7 on either side almost 80% of the time for the last 24hrs! Just caught him and did a 5 min fresh water dip but couldnt seem much with my eyes and reading glasses but now have him in a 2 part Blue lIne Lock QT dip/bath (15 mins part A and 20-30 mins part B) and back to QT he goes. Will catch remaining Purple, Yellow, hippo and Dejardi and Tonami tangs over next 24hrs and do the same I think is best now as the all did ok in QT for 30 days before DT. So far they show no signs but at this point I don't trust the DT system. Agree or am I being paranoid? I wonder could the remaining fish that survived the first episode the two Australian Stripies and my large maroon clown be carriers or something as they made it thru the 1st crash plus QT since Dec thru end of March and are in the DT now doing ok....so far.

As for DT...I think best option is to drain the whole thing. Pull the rocks. Transplant the few coral pieces and inverts I have into my 10 gallon tanks (have 2 empty ones) but how do I treat them as they are in a "wet" system? DT should I just reset it all AGAIN after bleaching it...but this time removing ALL rocks and Sand and just sterilizing the whole thing? Basically new system clean??? Am frustrated as let it sit fallow from Jan thru end of March and still this has happened. Makes you want to quit the hobby man! But appreciate all assistance and antidotes.

Do you have a microscope? You could look at some fresh dip water at about 80x and see if there are flukes.

The blotchiness of the sohal looks like flukes. How does it look this morning? I suspect that the mimic tang didn’t make it through the night?

The timing and circumstances of this does not indicate velvet; the stripeys are still in the tank and symptom free, right?

I can’t remember in the previous case, did you ever run hyposalinity?

 

[mdrobc13]

Do you have a microscope? You could look at some fresh dip water at about 80x and see if there are flukes.

The blotchiness of the sohal looks like flukes. How does it look this morning? I suspect that the mimic tang didn’t make it through the night?

The timing and circumstances of this does not indicate velvet; the stripeys are still in the tank and symptom free, right?

I can’t remember in the previous case, did you ever run hyposalinity?

Mimic did NOT make it through the night...yes. Probably passed soon after adding to QT and found him DOA this AM. Sohal is looking better and swimming around QT now. No distress or surfing near surface. Of course he doesn't have a wavemaker in the QT to surf though. He was freshwater dipped for 3-5 mins and then part A dip 15 mins and part B dip in Blue Line Lock with airstone before going into QD.

No new fish have been added to QT do do NOT think velvet as everyone added came from QT and at least 2-4 weeks of it. Longer time for stripies and maroon tang. Strippies and maroon are still in tank and not flashing. Those 3 are the ONLY fish from the DT prior to the 1st outbreak that went to QT and made it thru copper at 2.4 ppm since Dec thru mid March. The Purple tang and Yellow tang and Desardi and Tonami and Hippo tang are new additions and went direct to QT for 2-3 wks min and then to DT and they are currently in tank still and moving about this AM looking for food. Purple is harrasing the other tangs a bit but none looking splotchy or pump surfing. Don't see any flashing either although elbi tang and sohal and Gold RIm looked to be doing it some before symptomatic swimming began later.

Unfortunately no microscope available here nor at nearest LFS. Trying to decide IF a complete tear down in necessary....other extreme is to treat DT with copper....am really not looking forward to that option. On day 3 or Prazi pro to DT. Video of this AM behavior. Only other thing I have going on is an algae outbreak as you can see on the rocks from adding too much coraline accelerator and Radion Blues at 100%! :(

 

[mdrobc13]

Sorry to hear about the recent losses. This situation sounds very frustrating! Since the DT ran fallow for so long it seems unlikely that the DT was the issue. It seems more likely that the fish were continuing to harbor some sort of fish disease. Copper unfortunately only addresses some fish disease. The diseases copper does not address may be what did the Gold Rim Tang in.

Agree and Gold RIm was in QT for about a month in copper and then had a dose and 2nd one of Prazi in QT before moving to DT. Not sure if harrassed by Sohal and whatever harboring revealed/exposed and died from that and now Elbi infected and Sohal also. Other fish normal acting this AM but don't think that means all is well in the DT necessarily now that sohal is back in QT. :(

 

[mdrobc13]

What you’re describing, sounds like, and could be velvet. Flukes will not kill that fast. If I’m reading your post correctly your gold rim died pretty fast. I do not know of flukes killing that fast.

Were the fish flashing? Or just riding the current for oxygen?

With flukes Fish can become lethargic, swim near the water surface, develop clamped fins, hide in the corner of the aquarium or behind rocks, lose appetite, shake the head, flash, or scratch. They may exhibit yawning, cloudy eyes.

One extra thing to look for is swollen gills.

But to got from eating one day to dead the next it would take a crazy amount of flukes and at one point you would see the issue with the fish way before it dies.

No Gold Rim has been in tank since 1st week of April...was doing okay till he wasn't last week. THen found Elbi tang last PM. He didn't survive night. Sohal has been pump surfing for two days now. Is now in QT. Yes some flashing noticed for Sohal and Gold RIm. Elbi was near surface when I got him. Not velvet...seen that and ALL fish came into DT from QT after 2-4 weeks QT period at 2.2-2.4 ppm Copper and a dose of Prazi pro also and were added a week intervals to DT over 3 weeks..in pairs to avoid aggession. :(. System did 6 wks plus fallow plus added in sump UV...only thing added earlier than 6 weeks fallow were CUC which Jay H and other say may be what may have transfered whatever this is in the tank. But yes I AM perplexed. Been in the hobby since 2008 and NEVER seen this before.

 

[winxp_man]

No Gold Rim has been in tank since 1st week of April...was doing okay till he wasn't last week. THen found Elbi tang last PM. He didn't survive night. Sohal has been pump surfing for two days now. Is now in QT. Yes some flashing noticed for Sohal and Gold RIm. Elbi was near surface when I got him. Not velvet...seen that and ALL fish came into DT from QT after 2-4 weeks QT period at 2.2-2.4 ppm Copper and a dose of Prazi pro also and were added a week intervals to DT over 3 weeks..in pairs to avoid aggession. :(. System did 6 wks plus fallow plus added in sump UV...only thing added earlier than 6 weeks fallow were CUC which Jay H and other say may be what may have transfered whatever this is in the tank. But yes I AM perplexed. Been in the hobby since 2008 and NEVER seen this before.

I was re-reading over all the other posts. It would indicate flukes in the end. The part that made me think that velvet might be a thing is when you said he died suddenly after eating just fine. So a week of this issue is a different out take. Was there flashing or yawning during that week? Again the usual for flukes is they also don’t eat? To eat on Thursday and dead Friday am have not heard of flukes killing in such a way. You tend to see the issues, if you’re always keeping an eye out on the fish, way before they die. It is interesting for sure.

Have you looked at the gills of the any of the fish? Swollen? Or normal?

As for cuc being the culprit…. It would not surprise me. I decided to have a fallow tank that I use for corals, inverts and anything else that can possibly have diseases brought into my DT’s.

I got ich in my DT from a LFS that sold me ogo algae. Their fish tanks are full of all kinds of diseases, but they go in with their hands in the fish tanks, then dump them into the algae when you tell them you need algae without washing or drying off completely. Watched ich survive on a pin drop of water for 5-6 hours in 64-55*, under a microscope. It is insane. So it wouldn’t surprise me. If the only new thing introduced is cuc.

 

[Jay Hemdal Verified Community Expert]

Mimic did NOT make it through the night...yes. Probably passed soon after adding to QT and found him DOA this AM. Sohal is looking better and swimming around QT now. No distress or surfing near surface. Of course he doesn't have a wavemaker in the QT to surf though. He was freshwater dipped for 3-5 mins and then part A dip 15 mins and part B dip in Blue Line Lock with airstone before going into QD.

No new fish have been added to QT do do NOT think velvet as everyone added came from QT and at least 2-4 weeks of it. Longer time for stripies and maroon tang. Strippies and maroon are still in tank and not flashing. Those 3 are the ONLY fish from the DT prior to the 1st outbreak that went to QT and made it thru copper at 2.4 ppm since Dec thru mid March. The Purple tang and Yellow tang and Desardi and Tonami and Hippo tang are new additions and went direct to QT for 2-3 wks min and then to DT and they are currently in tank still and moving about this AM looking for food. Purple is harrasing the other tangs a bit but none looking splotchy or pump surfing. Don't see any flashing either although elbi tang and sohal and Gold RIm looked to be doing it some before symptomatic swimming began later.

Unfortunately no microscope available here nor at nearest LFS. Trying to decide IF a complete tear down in necessary....other extreme is to treat DT with copper....am really not looking forward to that option. On day 3 or Prazi pro to DT. Video of this AM behavior. Only other thing I have going on is an algae outbreak as you can see on the rocks from adding too much coraline accelerator and Radion Blues at 100%! :(

I could only get the first video to play - the one with the purple tang posturing at the yellow (that may not end well). From what I can see, this is gill flukes. I find that 30 days of hyposalinity at 1.012 works well for this - but of course, no invertebrates in the tank.

 

[winxp_man]

I could only get the first video to play - the one with the purple tang posturing at the yellow (that may not end well). From what I can see, this is gill flukes. I find that 30 days of hyposalinity at 1.012 works well for this - but of course, no invertebrates in the tank.

Hypo works for a majority of marine flukes yes? And I’m curious how fast it starts working once the fish is at the level of 1.012.

 

[Jay Hemdal Verified Community Expert]

Hypo works for a majority of marine flukes yes? And I’m curious how fast it starts working once the fish is at the level of 1.012.

It’s pretty quick to kill adult flukes, in a few hours. The 30 days is needed because hypo doesn’t kill fluke eggs, it just keeps them from hatching, and they then, they can’t hatch after about 21 days, so they die of “old age”.