I need some assistance with some sick/dying Cory's
I have a 75g tank, EC substrate, currently low lighting, moderately planted and stocked at about 90% as per AQadvisor. The temp is set at 77, ammonia is at 0, nitrites 0 and nitrates around 20ppm.
I added 8 albino cory's on Easter. Two days later while picking up a few more fish, I bought and then added two more cory's for a total of 10. I acclimated them by adding tank water to their bag every 15 min for an hour and a half. The next day after adding the two new ones, two were dead and since then, I've lost another one every other day. The fish came from Petco...
The fish look fine one day, then the following morning, one is dead. Last night, the 3 remaining looked great. Swimming all over the front of the glass as they usually do, feeding off the bottom, making an occasional run for the top and diving back down, etc... Then this morning I looked and another one was upside down in the back of the tank. I went to take him out with a net and as I was taking the net out of the tank, he tried to swim away... upside down, but he tried to swim away. I ended up taking him out of the tank regardless.
They are small, maybe an inch long. I've looked at them and physically, they look fine to me. My water parameters should be fine for them. I feed them Ken's flakes and catfish pellets. I've never actually seen them eat them though...
Any thoughts or ideas on what me be going on? I haven't been able to find any answers or even suggestions as to what may be killing them. My daughter loves them as they are very active and I would like to keep some in the tank, but have to figure out what is harming them first.
I have 4 Bolivian Rams, 7 Guppies, 15 Cardinal Tetra's, 11 Sunset Platy's, 10 Oto's and now 2 Albino Cory's.
It's just odd that they seem fine and then the next morning, there is one dead... I did have one Sunset Platy die a few days ago, but I think he got himself stuck in a small hole in a piece of driftwood... He was in the hole, when I went to get him with the net, once he free'd up, he floated up to the top very fast. So I'm assuming he got himself stuck since he stayed there until I disloged him. Other than than that, I haven't lost any other fish...
Any advice would be greatly appreciated.
These are Petco fish, so I called Petco, spoke to the manager and explained the situation, he said he would check into it and call me back. He did call back and seemed like he genuinely looked into and they weren't aware of any issues with the shipment of cories that mine came from.
I don't know what else to do or what to check at this point... I would like to add more, but don't want to subject them to whatever is killing off the current ones and I'm concerned about it possibly being a disease that can spread to the rest of the stock.