Rummy nose losing color!!!

[JuiceBox52]

Can anyone tell me why some of my rummy nose tetras are losing some of the red in their tail?
55gallon
Ammonia just above 0, doing water changes to lower it
Ph 7.0
Nitrites and nitrates good
Tank mates: 2 otocinclus catfish, 1 guppy, 6 rummynose, 4 neons

 

[Byron]

Do you mean red on their heads? There is no red anywhere else on rummynose tetras.

Loss of colour can be due to various things. Ammonia (or nitrite or high nitrate) certainly is one; what is the actual ammonia reading, and what test are you using? And do you have live plants?

The pH is 7 but what is the GH (general hardness)? You should be able to ascertain this from your water authority, check their website (assuming you do not already know the GH).

When posting issues, always give the actual numbers for any tests. Nitrates "good" can mean something very different to me than it would to you or others.