Individual fish dying one after another in two different tanks

[Max]

Hello,

I currently have an unprecedented amount of problems with fish dying slowly over time (things started maybe 6-8 weeks ago, it does not seem to stop), which really takes away the joy of my aquarium hobby. I hope some of you might be able to help me.

Up front, all usual water parameters are fine (gH 13, kH 11, ph 7 to 7.5, normal nitrate, no nitrite / ammonia). Water temp is 26-28C / 78-82F in my 350L/75G and 21C / 70 F in my 50L/13G aquarium, but was 25C at the point where the honey gouramis were still alive). My other aquariums (2 endler guppy tanks at room temp with the same water parameters (also unheated at 21C)) show no problems at all. Water change schedule is 40% every 2 weeks. The 350L is already running for 1,5+ years, the 50L is only a few weeks/months old.

Stocking: The 350L tank has 3 adult angelfish, 2 german blue rams, 3 L181, 30 amano shrimp, 4 nerite snails, rummynose tetra, Hyphessobrycon melanostichos tetra, 12 otos (1 left, others died), around 18 panda corys (maybe 5 left, others died), 10 gold laser cory (9 left, 1 died a few days ago). The 50L tank had 2 honey gourami (dead), 8 neon green rasbora (dead), 3 endler guppies (dead), neocaridina shrimp (all alive) and 8 dwarf kuhli loaches (Pangio cuneovirgata, 6 left). 

I am not 100% sure that both tanks have the exact same problem, but the problems are similar. Every few days, a fish dies. For the most part, the same kind of fish died in order: First nearly all my otos, then starting to also affect my panda cories, now starting to affect my gold laser corys. All other fish are fine for now. In the 50L tank, it was basically all mid water swimming fish together (still only one dead every few days), only after all mid water fish were dead, did it start affecting the dwarf kuhli loaches. 

The fish are fine until they are not, in which case they start showing signs of bad health (washed out, maybe red spots) for a few days. Some of the otocinclus and panda cories were eaten alive by my amano shrimp, showing no power to defend themselves. I was able to finally film a dwarf kuhli loach before dying, which you can see below. The odd one out was my male honey gourami, which already had some brown spots for a while and was doing fine, so I’m not even sure they were the problem (he was pretty old). 

I have no idea what could be the problem, I did have bacterial problems in the past but why does it happen to healthy fish and slowly over time? The only thing connecting the two tanks is that both got fish in it that were at some point in my quarantine setup together (the rams were there a 6-8 weeks before going into my 350L, but they are very healthy). The neon green rasbora and some endler guppies were in that quarantine tank as well, but some of the endlers went back to their original endler tank where there are no problems.

One think I suspected were internal parasites, but I have so many shrimp in both tanks and all parasite medicine is deadly for the shrimp, I guess my next move would be to try to get out as many shrimp as possible, then medicate? I have no idea how I will get them out, probably would need some form of trap.

In the attached images, you can see: Healthy angelfish, one gold laser cory dying slowly (2 days between pictures, dead 2 days after last picture), oto 1 day before death, panda cory 2 days before death. The 50L aquarium, endler guppy still healthy (probaby 2-3 weeks before dead), honey gourami pair still healthy, group of dwarf khuli loaches healthy, the first dead kuhli loach, the second dead kuhli loach (I am not sure if the black thing on the rist is my black sand, probably but it was attached to the kuhli loach, maybe swallowed?). Then my male honey gourami a few weeks apart, the last photo being a few days before his death. Also a neon green rasbora with weird red part in its tail, probably 2-3 days before its death.

Finally, here is a video of my second kuhli loach before dying: https://streamable.com/zq0d7j
I can also upload further video of the oto and panda from the images, basically they are just heavy breathing (on that note, both aquariums have air stones/air bubbles via the filter output).

I really tried to keep it short, I don't think I succeeded and I am sorry for the wall of text, I can answer further questions if needed.

Edited September 28, 2022 by Max
smaller images

[Colu]

Is it always after a water change that you start to lose fish and do you use a water dechlorinator like prime when doing water changes any rapid breathing hanging near the surface sunken belly's spitting food out flashing 

[Max]

No, the dying is independent of water changes as far as I can tell. Yes I use dechlorinator, though I am from Germany where there is little chlorine. I did only start losing fish in my big tank after doing a deep clean of my internal filter, which I did not do for many month and it was quite dirty. But that would not really explain the same problem in the other tank... (if it is the same problem).

Once the fish appear ill, they do breathe heavy. The other fish act normal with normal breathing. They also get sunken beys I would say, yes. At least the corydoras did. The corydoras also stayed near the top on top of leaves sometimes which is unusual. Not sure about eating behavior, it is possible they spit out food or eat less.

[Colu]

On 9/29/2022 at 12:22 AM, Max said:

No, the dying is independent of water changes as far as I can tell. Yes I use dechlorinator, though I am from Germany where there is little chlorine. I did only start losing fish in my big tank after doing a deep clean of my internal filter, which I did not do for many month and it was quite dirty. But that would not really explain the same problem in the other tank... (if it is the same problem).

Once the fish appear ill, they do breathe heavy. The other fish act normal with normal breathing. They also get sunken beys I would say, yes. At least the corydoras did. The corydoras also stayed near the top on top of leaves sometimes which is unusual. Not sure about eating behavior, it is possible they spit out food or eat less.

It possible they are suffering from wasting disease you can treat with levamisole in food feeding a small amount twice a day for 7 days it's less likely to harm your shrimp when added to food and it's more effective or you can use fenbendazole in food feeding once a day for 3 days and repeat in two weeks

Edited September 29, 2022 by Colu

[Max]

Thank you for your reply. I am not sure how easy I can get these here in Germany. I went to the local fish store to get additional medication but there was nothing with your listed ingredients, is there anything that might be appropriate what I already have?

• sera mycopur (anti-fungal and against gillworms) with Acriflavine and copper (chloride and sulfate)
• sera costapur F (anti ich and other parasites) with malachite green oxalate and Formaldehyde
• eSHa EXIT (anti ich) with methylene blue, Ethacridine lactate, malachite green oxalate, methylrosanilinium chloride
• eSHa 2000 (multi purpose) with Ethacridine lactate, copper oxide, Methyl orange, Proflavine

And would it be possible to also use any of these with the soak method as well?
For wasting disease, I found this post (https://www.fishlore.com/aquariumfishforum/resources/wasting-disease-fish-tb.200/)  which also recommended "heavy antibiotics", I also have some antibiotic medicine.

[Colu]

On 9/29/2022 at 7:51 PM, Max said:

Thank you for your reply. I am not sure how easy I can get these here in Germany. I went to the local fish store to get additional medication but there was nothing with your listed ingredients, is there anything that might be appropriate what I already have?

• sera mycopur (anti-fungal and against gillworms) with Acriflavine and copper (chloride and sulfate)
• sera costapur F (anti ich and other parasites) with malachite green oxalate and Formaldehyde
• eSHa EXIT (anti ich) with methylene blue, Ethacridine lactate, malachite green oxalate, methylrosanilinium chloride
• eSHa 2000 (multi purpose) with Ethacridine lactate, copper oxide, Methyl orange, Proflavine

And would it be possible to also use any of these with the soak method as well?
For wasting disease, I found this post (https://www.fishlore.com/aquariumfishforum/resources/wasting-disease-fish-tb.200/)  which also recommended "heavy antibiotics", I also have some antibiotic medicine.

None of the medication you listed are effective against wasting disease you should able to ESHA ndx active ingredient is levamisole or NT labs fluke and wormer active ingredient is flubendazole that is effective against wasting disease 

Edited September 29, 2022 by Colu