Peppered Cories Dying Randomly

In my 60 gallontank I had 4 peppered cories for about 6-7 months. All of a sudden I've lost three in the last week or so. I have angelfish and mollies in there too.

Ammonia 0
Nitrite 0
Nitrate 40
ph 7.6
temp 80

They all seemed perfectly fine and then turn up dead one at a time. None of my other fish have showed any problems except one molly that had a little fungus I treated very swiftly a few weeks ago.

I have one left. Do you think I should move it to my 55 that has 4 albino and one juliI so it's not alone, or try to buy more peppered and hope they live? I know my temp is a bit high for peppered so maybe I shouldn't get any more.

 

What are you feeding ?

 

What are you feeding ?

omega one veggie flakes, northfin 2mm pellets, and frozen foods occasionally like brine shrimp and blood worms

 

omega one veggie flakes, northfin 2mm pellets, and frozen foods occasionally like brine shrimp and blood worms

also an omega one algae water every once in a while.

I have sand substrate, lots of live plants, terra cotta pots for shelter, wood for my pleco, a cascade 1000 filter, and floating plants too

 

So all deaths occurred after you treated the molly's fungus?

 

it didnt seem to be related but the only two possibilities I can think of are nitrites in my tap and not enough prime, or toxic gas building up in my sand.

 

How does the remaining one look ?
I'd swap the veggie rounds for shrimppellets or so.

 

How does the remaining one look ?
I'd swap the veggie rounds for shrimppellets or so.

the remaining one looks fine. it's impossible to get food to them unless I overfeed the tank because my angels are such voracious eaters! I'm thinking about moving it to a different tank that has other cories in it

 

Think about crushing food to dust. Corys will find them, angels won't be interested.