Sudden panda cory losses 2–3 days after adding a new group — could this tie back to earlier panda deaths?
29g planted community (rasboras, neons, 2 honey gourami, 1 Bolivian ram, 2 otos, and a stray guppy that hitchhiked in). Heater is set to ~76°F but the thermometer usually reads ~74°F. HOB filter with the outflow turned up. Weekly 25–30% water changes.
Timeline:
About two years ago I started with 6 panda corys from my usual LFS. Over the next couple of years I lost 3, spaced out by months—sad but not shocking—so I was sitting at 3 pandas. This past Saturday (Nov 1) I picked up 6 more from a different, closer LFS. I floated the bags ~30 minutes for temp and did my normal quick transfer. They looked fine at first. By Tuesday (Nov 4) I found 5 dead (through the day) and then one more later. At that point ammonia was 0.25 ppm—I’m assuming from the bodies. Nitrites is 0, pH is 7.4, Nitrates around 20ppm. I pulled the fish, did a 30-40% water change 29-g tank), dosed Prime, and cranked the filter flow. Everyone else in the tank looks normal.
What I’m trying to figure out is why the crash happened 24–72 hours later and whether it could be related in any way to my earlier panda losses (even though those were spaced out over months and felt like normal attrition). Over the past 2 years, I haven't had any confirmed deaths other than the panda and the occasional RCS. Was this just a rough batch or a water-difference mismatch with the new store, or is there something about my setup that only pandas are sensitive to?
Also open to concrete tips on acclimating pandas from LFS systems that might run different water than mine (what’s worked for you in that exact scenario). Thanks.
Posted Nov 5, 2025, 1:50 AM UTC