Panda Cory Dying!

[skimmy290]

a little while ago i bought 2 panda cory for my 55 gallon planted tank. A week later i ended up 2 more so they could keep each other company. the other day i saw one dead and now today i can't find another. I don't know if it's the new ones that are gone or the old ones but now i only have two. My ammonia and nitrite are at 0 and nitrates are at 5ppm. I take out 5 gallons every other day. any ideas as to why this is happening ?

 

[Cory_Dad]

Did you quarantine the 2 new ones for several weeks before putting them into the tank with the others? They possibly could have been sick.

 

[skimmy290]

ah.. no.. i'll admit i didn't quarantine them, i was a bit too excited and i just put them in after acclimating them