Fish are dying

[11k]

soo I just came home and found 2 fish dead - today was one of my Cories and a pleco

yesterday was a cardinal tetra and German blue ram.

day before was a neon black skirt tetra and another corie

I checked my water parameters - PH is a 8.2, nitrite zero, ammonia zero and nitrates 0-5. tank temp is 79.2. (I just turned it up again as someone mentioned it could be ice.

25% water changes happen weekly with including a gravel vacuum. its 75 gallon tank that has been running for about 6 months. I use a 110 aqua clear filter along with 3 sponge filters.

currently stocked with 6 rainbows, 3 cardinal tetras out of 11 as of last Sunday, 5 neon black skirt tetras, 2 dories, 2 African drawf frogs, 1 German ram and 2 guppies.

I feed them flakes and slowly sinking blood worms plus sinking shrimp and algae wafers.

not sure what I can do to stop the deaths from occurring???

everything was going smooth until I added 4 cardinal tetras and 3 neon tetras last Saturday.

 

[fearlessfisch]

I don't know, but, personally, I would do a major water change (80 to 90 percent) just in case something bad got into your water. Match temperature carefully and use dechlorinator. Did the dead fish show any signs of disease or trauma? Are you seeing any change in appearance or behavior in the other fish? If so, what do you see/what are they doing?