Last night during feeding time, I performed my nightly headcounts and health checks. I watch the tank constantly, but feeding time is the best time to get counts and look closely at each fish. Everyone was absolutely fine to my eye. Happy and healthy.
This morning, I turn the tank lights on and immediately notice that something is terribly wrong. One of my DP girls had white "stuff", for lack of a better term, covering about half of her right side. She was bumping into things and did not appear to be able to see out of her right eye, or move her right fin. I assume that her gill movement on the right side was also restricted. My instincts told me that it must be some sort of fungus, but how could this overcome her literally overnight?
I flung a quarantine tank together as fast as I possibly could, but by the time it was set up and ready to move her in, it was too late. She was gone. I had a good cry before I got the camera out to take pictures to show you all, as I really need to know what this is not only for closure, but because I am very frightened for the rest of the tank.
Before the pictures, water parameters and other information.
0 ammonia
0 nitrite
20 nitrate (Planted tank. Never goes below 20.)
Water kept at 80 degrees F.
50% water changes, twice weekly, with Prime.
3x weekly plant ferts and Excel
30ppm CO2, measured via drop checker
5 otocinclus + their fry
7 kuhli loaches
5...4, I mean, dwarf puffers. (I got these just last week. 1 is still being treated for IPs, but the others are clear. Eating well and excellent feces.)
Let me know if I forgot anything.
Click the pictures to enlarge them and get good looks.
First two pictures are her right side with the affected area. I attempted for one picture to look how it looked in the water, which is whiter than the pictures can depict.
The last picture is her left side, which is normal, for comparison.



Whatever this is must surely be terribly aggressive for it to have manifested and killed my poor girl overnight.
Everyone else in the tank looks fine at the moment, but I know that I can't trust that now.
What can I do to treat the tank and kill off whatever is causing this? Pimafix/Melafix? Salt?
I'll be doing an extra water change as soon as I pull myself together here.