HELP I'm Freaking OUT

[23jim]

Alright two days ago I found three dead cardinal tetras. Not to worried as I added five a week ago without a quarantine (I know I get what I deserve!, but I observed them at the store for over two weeks. Yesterday lost four more (UGH more than just lack of acclimation) and one of my Corys. Today lost one more cardinal and one cory. Started treating with Melafix yesterday. One more of my corys looks bloated on his belly and not very active. None of the fish are eating much. Black neons all look good, Bolivian Rams also look OK although not eating much. One cardinal look like white covering on eye and is swimming more alone, another cardinal sometimes swimming at a 45 degree angle and hangin out near top. I am freaking out that this is either Neon Tetra disease or worse yet TB!

I did big water change (25%) on day one of episode. Today Nitrate and Ammonia look fine, I did not check them before water change. pH is High (more than any of my scales read, but cory's have been in tank for over a month doing fine till now) and the water is VERY hard also.

The corys all lost their coloring and turned pale a couple of days ago but it came back today. The cardinal with the white slightly puffy eye is the first specific symptom I have seen.

What do you think NTD or TB or something else

 

[blert]

What are the actual numbers for ammonia, nitrite and nitrate levels?

 

[23jim]

I think they were 0, 0, and 20-40 ppm nitrate. The water temp is 78 F, the tank has been fully cycled. I did use a 2-1 ratio of RO water to tap in an attempt to lower hardness and pH for the 1st time on my water change when this 1st showed up two days ago. The water mix was still pH of 7.4 ish and 100 ppm GH. My tap is 300+ GH and 300+ KH. I only did about 6 gallons of a 30 gallon with this mix but maybe this was enough to hit the cory's? My two ottos look the best in the whole tank so I don't think it is a water Quality issue, maybe a pH change problem, but really, I did not change it quick as I did the water change in stages over 6 hours.

 

[23jim]

Another dead cardinal this morning, his stomach looked bloated a bit. Another one swimming sometimes at a 45 degree angle. Would like to try something besides Melafix if anyone thinks that may be helpful and not just stress them more, anyone got any recommendations? The cory that looked a bit ill yesterday is still alive and seems a little more active.