Disaster in my tanks!

[jeaninel]

Ugh, tough start to the weekend. First, all the fish in my QT are dead....3 large Roselines, 2 SAE and 5 baby bushynose (not all are shown in the pic). The only survivor is a lone White Cloud. I suspect one of the Roselines brought in something, possibly columnaris. The night before I discovered one of the Roselines floating. So I fish him out. Everyone else seemed fine. The next day... everyone else is dead! Except the one little White Cloud. Tough dude.

Then tonight in my 135 I see one of my three Leopard Ctenopomas spazzing out. I look closer and he has a Cory stuck in his mouth! They've been living together for years with no issues. I couldn't save him. He was a hair under 8" long. One of my favorite fish. RIP buddy.

 

[duanes]

Sorry to hear about the deaths...
In actuality, your QT tank did exactly what it was supposed to do, allowing whatever disease the new fish were carrying to act in QT, but not spread to the main tank. I would consider that lucky, in one sense
......
On the other "predatory event", this is one of the many reasons I don't keep fish from different continents together in the same tank.
All Corys have spines that catch in the mouths of predators, so any predators from S America that eat Cory's have developed strategies to deal with those spines, or die.
old world species like Ctenopoma's have not had to evolve in that way because they would never be found with, or have a chance to prey on Cory's.
As an example, when the guts of oscars in nature are opened, they are often filled with Cory cats they have eaten, because they have adapted astrategy to deal with the spines, and survive.
Once your Ctenopoma became large enough, being a piscavore it was inevitable that it would try to eat the Cory?
But has not evolved instinct, or strategy to enable it to deal with the consequences.
The Ctenopoma might have had the same problem if kept with a small enough clown loach that have similar spines, being Asian, and never the twain shall meet,

 

[EricTheRed]

This is the sole reason I swore off Cory’s decades ago. Most of my fish get large enough to eventually decide to eat the diminutive Cories. Cories are very cool but I haven’t lost a single fish to this issue since permanently banning the spiny Cories from my aquariums

 

[Backfromthedead]

Apologies for your loss. Careful to clean off any equipment and decor that might go from the qt tank to other tanks and contaminate them. A lot of pathogens/parasites can survive for quite awhile out of water.