Dieing Fish-- Disease or natural???

[Malachite]

Hello all. Tonight one of my blue Zebra Danio's is dieing. He started swimming a little weak yesterday and today he can only hover on the bottom. I double checked the water and PH, Ammonia, Nitrites and Nitrates appear ok. He was one of the six danio's that was used to first cycle the tank. I know the nitrite levels were very bad during my cycling and I am thinking he was just week. It has been almost two months since the cycling completed. I don't see any apparent disease hints. I was hoping everyone else would tell me if they see anything. Thanks.

 

[Harlock]

When you say the numbers are just fine, what do you mean? Also, cycling with fish can Severely impact their life span.

 

[Malachite]

When you say the numbers are just fine, what do you mean? Also, cycling with fish can Severely impact their life span.

Here is a pic of the vials. PH, Ammonia, Nitrite, Nitrate. Hopefully. I am not stupidly reading something wrong.

 

[TONO]

well if thats an aquarium pharmasuticals (sp) test kit your ammonia is about .25ppm. Ph looks good and nitrite is fine do a small water change. One question though what do you mean when you say its already cycled? Do you have visible nitrates?

 

[Malachite]

well if thats an aquarium pharmasuticals (sp) test kit your ammonia is about .25ppm. Ph looks good and nitrite is fine do a small water change. One question though what do you mean when you say its already cycled? Do you have visible nitrates?

Just for reference the picture was about two hours old. I forgot the brand it is but the instructions say to wait five minutes and then check color. In between the five minutes and me taking the picture it darkened a little bit. By this morning it was very dark. I am assuming that this is normal. I hope it is not a bad test kit!?!

I think I have an answer to the nitrate question. I currently only have 8 inches of total fish in a 75G planted tank. I think I may have enough plant coverage to absorb most of the nitrates. I have started doing weekly water changes now of about 15%. I think the remaining nitrates went there.