I have a 20 gallon tank with platies, mollies, and cories. I had 6 albino cories for the longest time, at least a couple of months and they were fine, and active. Recently I went and got 3 Juli cories and they seemed fine so I added them to the tank. One of them died after a week so I brought him back and got another then two more Juli cories died after 2 more weeks then my last Juli died a couple days after and the day after one of my albinos died and now, three days later another albino cory died.

After I found the second Juli died I did a 50% water change. I checked the PH, it is a little high, but within the accepted range. The filter is fine. I have 3 plants.

Now the remaining cories are just hudled in the corner, only moving to go to the top. These are my favorite fish, I don't want anymore to die, I just don't know what to do. My other fish are perfectly fine.

Any help is appreciated!

Cories are very tough fish and hard to kill. Their ph should be below 7.5, low Nitrates, temp below 80 and no mean fish in their tanks. They also like some plants and rock to hide among. Try and practice more frequemt water changes than you have in ther past. If you can, test your Aquarium water and your store's, it sounds like there is a big difference.

I do a 20% water change ever 5 days, and none of my fish pick on them. but thanks.

I've never heard of Cories being a tough fish.... Do you check your nitrate level often?