I have a planted 29 gallon and this week I lost a betta, 10 CPD’s, & 10 cardinal tetras within 4 days. The only abnormality I noticed was a tetra had developed a single white dot on its side that looked like a pimple. No loss of appetite and was very active along with the others. I still have 1 pintail red wagtail platt, 6 cory’s and 8 amano shrimps. They seem normal. I’ve found most dead except for one tetra that I saw. It was just floating, trying to keep itself upright. The day before most died I happened to over feed them. Slip of the hand. Could that have caused this?
I do weekly water changes and water has been stable for years. I keep the temperature at 78. I know if I’ll lose more fish, but I’m not sure how to proceed. Should I do anything to the fish tank in case it was a disease or wait a few weeks and see how it all plays out?
My water parameters have been as follows:
nitrate: 20
nitrite: 0
gh: 200
chlorine: 0
kh: 80
ph: 7.2