what temperature are you keeping your peppered cory(s) at? They should be kept at 18-20°C and no higher than 23°C
Well atm the main tank is at 30°C for white spot treatment A good water temperature can range from 70 to 78 degrees Fahrenheit which is about 22 -27°C, usually i keep my tank at about 25°C. I got this information from here on the fish species place peppered corys
that's cool. it's just the peppered corys in particular should be kept cooler than most other corys and higher temperatures will simply shorten their life span.
By the way how do you make the "degrees" symbol? lol i just copied and pasted yours
if you keep hold of your Alt key and type 0176 then let go of Alt you should get °
..there are many others too
¼ (Alt+0188) ® (Alt+0174)
http/www.coyotetale.net/ascii/index.php
Have fun lol