Mortal disease: treatment ?

[kiwidu21]

hello,

I am having a big problem with my corydoras. A few months ago I welcomed 5 wild corydoras duplicareus and 5 farmed panda corydoras.
During quarantine I noticed that some were developing symptoms:
- weight loss
- red gills
- difficulty breathing
- change in color (the creamy white became flashy white).
I treated with cattapa leaf first. As that didn't work, I used esha 2000 (general treatment) and esha ndx (dewormer). It works for a while then they relapse. So I end up with deaths from time to time, always with the same symptoms.
Only the corydoras are affected, the hypancistrus, oryzia and other fish which are in the same tank have absolutely nothing.

Today I have 3 duplicareus left, one of which is sick as well as a panda who is also sick. I bought black Venezuela from a private individual but I have the impression that they suffer from the same disease (I immediately quarantined them with the same treatments as before).
I looked at the water parameters and everything is good:
ph: 6.5
ammonia: 0
nitrates: 5
nitrites: 0
conductivity: 84 microsiemens
temperature: 22°C

I saw that it could be bacterial but esha 2000 would have, in this case, solved the problem.

Do you have any idea what my corys are?

[kiwidu21]

Nothing ?

[JamesFish]

Few things to consider.

Esha 2000 is well tolerated but not the most powerful of medications its possible it knocks back the issue but can't clear it.

The disease you are fighting may well be a small parasite and as such the meds knock out some stages but not all of them so as it cycles your fish are reinfected. You may need to treat for a longer length of time. I know that's annoying and expensive.

[aquaholic]

Sounds like gill or skin flukes but without a microscope check everything is speculation.

Do you have access to a low powered microscope? Even a cheap USB or plastic kids microscope is sufficient for 200X magnification. Some smaller protozoan parasites (example - costia) are harder to find than huge flukes but having a confirmed identification makes targeted treatment much safer and reliable, not to mention being able to confirm successful treatment afterwards.

Microscope use and parasite identification is merely another skill towards successful fish keeping. There isn't really an excuse not to learn. There would be heaps of youtube tutorials and online photos for ID if you don't want to invest in books.

[kiwidu21]

My phone takes good macro photos, could that be enough?
I can have access to a professional quality microscope (I have to check if I have the right to use it but also to take a slide. On the other hand, how do I take the sample? The corydoras are in a weak state but not dead. If I observe it under a microscope it will be at my work so it will have to remain in a container for at least 7 hours. As I work in the food industry and the living is prohibited, I could not put a bubbler on it otherwise it would awaken the suspicions.

Otherwise I saw this microscope: https://www.manomano.fr/catalogue/p/mic ... =119338601
Would the quality be sufficient?

[aquaholic]

There is a huge amount of information online. For example https://eshalabs.com/how-to-take-a-skin-scrape/

Corydoras are armoured fish which makes skin scrapes and visually spotting skin ailments much harder as the armor hides their skin (white spot for example is best identified behaviourally for corys). However gill snipes with sharp scissors is relatively easy.

Getting a sample to view is one step. Positively identifying a parasite (if any) is the next step. Luckily parasites need to be in large numbers to become a problem which makes finding them easier. Working out the best treatment regime is another step.

You need to work out the logistics for your own situations. One of the most satisfying aspects of fish keeping is that it's literally a sequence of problem solving events until you achieve the goal(s) you want.