panting

Hi all, New to this forum. I've had a betta for about two years and recently decided to expand into cories. My local tropical fish store is run by hobbyists and has high reviews, so I decided to trust them when I bought two pepper and one albino cory to accompany my betta in my 10 gallon tank...

I noticed a couple of days ago that my big female bronze cory was panting. Normally they move their mouth/gills when eating food, but she does this constantly now and has never shown this behavior before. Other than her mouth/gills moving rapidly, she also goes up for air a bit more than usual-...

Tank size: 7.5 Gallons pH: 8.0 (I know it is high, it is just this area's water) ammonia: None nitrite: None nitrate: .5 ppm kH: high (as always) gH: high (as always) tank temp: 77 degrees Fish Symptoms (include full description including lesion, color, location, fish behavior): The betta has...