The 4 corydoras look good except the initial injured one, and he is still having balance issues.
I moved my 10 gallons out of the fish room today, so I won't have to heat it, and for a few minutes I put the white female Molly (see whirling molly thread with mama daddy and baby) back in with the corydoras. She immediately hid in the darkest place in the tank. And she'd been doing that in the 10 gallon. I euthanized her with clove oil. clove oil, I learned today, will melt styrofoam cups. Safe throwaway clove oil container go for paper or plastic. Anyway. I moved the 3 guppies who are healthy that were with Mrs. Molly into the 29 with the corydoras. Many years ago I dealt with enteric septicemia, a disease that hits kidney, liver then brain on fish. I can ID it on a guppy visually so if they were exposed, well the corydoras were in with the mollies for months, and I would be able to tell. If it is ES, I can deal with it or not, but mainly transmission is from eating the infected body of a fish that died and it kills pretty fast. I really don't think that is what this is.
The other disease I dealt with in the 90s that involved corydoras (but not mollies, but I didn't keep mollies at the time) was one that went from cory to cory, and it was a balance issue, then that fish would die and the next cory would get sick. And it killed several in one year, til I accidentally infected the tank with ich. I used Clear Ich to treat, its active ingredient was a quinine product, and the cory quit having balance issues after the ich treatment.
So today I am attempting research to see if I need to move the shrimp out before treating with Quinine Sulfate, which I have on hand, labeled for aquarium use. But shrimp aren't on the jar, so I did internet search about shrimp and quinine. I still don't know about shrimp, I'll move him before I treat the 29. But what I read on the american aquarium products website, under Quinine Sulfate/Hydrochloride.
"
USE: Quinine Sulfate/Hydrochloride is useful for resistant strains of Ich (especially on scale less fish), as well as Protozoan caused sliminess of the skin and Rams disease (symptoms of whirling disease).
Also useful for resistant strains of Hexamita when combined with Metronidazole.
When Quinine Hydrochloride is combined with Malachite Green, this is one of the most effective and proven Ich and similar single cell ectoparasite treatments available! AAP Super Ich Plus is one such product that combines both and is the Ich treatment of choice for difficult cases of Ich (although for sensitive fish such as Cory Cats & Loaches this product/combination should be used at half dose and combined with Triple Sulfa).
DOSAGE : 250 mg per 10 gallons of water. Once a day for 4-5 days. Do a 25% water change before each treatment. Quinine Hydrochloride is generally safer than Quinine Sulfate more effective when available."
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Aquatronics went out of business around 2000, they made Super Ich Plus. I had the chance to buy up their inventory and referred the storage facility selling it to Fritz Products, who do make and sell fish meds. (Being on the internet gets me interesting phone calls, lol) So Their quinine formulation is gone. But there is an Arizona lab that serves the big commercial aquariums and they have some. And I have some from them.
Note the Whirling disease mentioned in the first paragraph under use. Remember the whirling molly?
I suspect she was too far gone, but I also suspect that I'm going to dose the 4 corydroas and the 3 guppies that were in with her with Quinine Sulfate and see what happens.