Neon tetra fin turning brown?

I recently noticed that two of my neon tetras fins were starting to show a brown/black appearance. Is this a sign of any disease or just coloration? I don’t think they had this when I first purchased them. Another tetra in my tank may have gotten it too.

Tank: 20 gallons
6 neon tetras, lost 4 to Ich in quarantine
Temp 75° F
Nitrites 0 ppm
Nitrate <20 ppm
Water Hardness Soft
pH 8

 

Curious about a response, mine have this fin coloring without any detrimental effect, I never thought about it being an issue.

 

Curious about a response, mine have this fin coloring without any detrimental effect, I never thought about it being an issue.

Good to hear that yours are doing fine with it. Mine doesn’t seem to have any negative effects from it either- hoping it’s just some natural coloring but wanted to make sure it was nothing serious.

 

So I looked at my Neons a bit more closely. When they swim forward, the fins are folding a bit and appear darker, when the fish spreads out the fins they are just more translucent.

 

So I looked at my Neons a bit more closely. When they swim forward, the fins are folding a bit and appear darker, when the fish spreads out the fins they are just more translucent.

Interesting, mine seem to have that brown color as a permanent shade even when I change the lighting. Only two have brown and the rest have the translucent fins you described. I wonder if my high pH may be causing this?

 

Hard to say, I have a pH of 8, but there are so many factors. I would just watch them a bit closer for a couple of days.