It started a week ago. First was one of seven pencilfish (4 coral reds, 2 elegant and a purple) rescued from Petco between 1/26 and 1/29. I think the next to die was one of the elegants. Didn't think too much of it until some of my established fishing started dying. Over the course of the first few days of this week I lost one of 3 albino bristlenose, 1 of ~10 CPD, all 5 of or 6 cardinal tetras (one I found on the floor (very limited spot to jump out), some others had been all or partially eaten by shrimp), also found one shrimp dried out on top of the glass lid, 1 of 4 peacock gudgeons, and more pencilfish. Tuesday I medicated with the API general cure and yesterday I did the second dose.
This morning I found a black neon tetra dead, though this one had a bloated-looking stomach for several weeks but acted fine. I wasn't surprised to see it dead though I thought it had already died and been eaten by shrimp because I hadn't seen it for a few days. Everything else was fine around 10am. This evening I found the last pencilfish in that tank dead at the surface and attached to a powerhead that I only started using once I medicated (also added an airstone at the other end of the aquarium). At the bottom of the same corner was a dead neon.
All the fish looked perfectly fine except for the CPD that seem to have some bare spots on it's side and was struggling. I put it in a seperate smaller tank by itself and it was dead the next morning.
Initially I though maybe the pencilfish were getting really aggressive at night or something. One female coral red and the purple have been in a seperate 10 gallon with guppies since early this week and they're still alive.
I pretty much ruled that out aggressive fish. I've considered bad bloodworm which I fed a little bit of a couple days before deaths started. All the water parameters are perfectly fine.
So I figured maybe something internal, thus medicating the way I did.
I have a lot more fish in this tank, a 125, that I need to keep alive.
Fish from tonight. The neon's left eye looked like it might be bulging a bit.
One more CPD lost when I checked late last night. No more losses this morning. Everything looking good midday. Noticed my female albino cory swimming up and down at the front glass, then noticed her anal fins clamped. 🙂
A minute or two later she deposited two dozens eggs on the glass. I draped a spawning mop over them as some protection against getting eaten while they harden. I really need to get the eggs into the breeding tank. As much as Iike to move mom to it I don't want to introduce something.
That's wild.
The water changes weren't even cooler. I got it up to the same temp first. Hadn't done any feeding prep either.