Red Eye Tetra's Losing Black Stripes

We have 7 RET's and I've noticed over the past few weeks their black stripe on their tail fin is fading. Only one hasn't. Their eyes don't seem as red either.

The water has been tested, and is healthy. They are relatively new but seem to have adjusted to their new environment and seem healthy overall.

Even with 7, I still feel like they chase and nip each other which might have something to do with it. We have 29 gallon tank so plan is to get more RET's as I know they're schooling fish, but am hesitant to buy more considering this discoloration concern.

Thoughts? Advise? Thank you!

 

We need more information to try to help. What size tank? Can you post the actual water parameters for ammonia, nitrites and nitrates? Tank temperature? What other inhabitants are in the tank other than the 7 tetras? Pics of the tank and fish would be helpful as well.

 

HI there! It's a 29 gallon tank and has a pleco and a khulI loach. We're going to move the pleco into a larger tank. The goldfish in the pic is no longer in this tank.

Very interesting however, I was about to take a pic of the RET's and their black stripes are back. So weird, an hour and a half ago when I fed them and posted this the stripes were gone. Wow, they must change colors based on other factors such as night, light, food, etc.

Yay, they look great again!

Temp: 76°
PH: 7.6
High Range PH: 8.0
Ammonia: 0
Nitrites: 0
Nitrates: 0-5.0 range

 

Could be age. The fish in the pic looks okay to me.

 

Thank you. Yes, they're just fine now. It was so odd that within 2 hours their stripes were back. We only bought them a few weeks ago so I don't imagine they're very old.

 

Thank you. Yes, they're just fine now. It was so odd that within 2 hours their stripes were back. We only bought them a few weeks ago so I don't imagine they're very old.

Owww okay. Than they won't be old hahaha. 2 hours after the lights went on?

 

Yes! I turned the lights on at 6:00am and fed them, and they had no black stripes and even the red rings around their eyes were faint. It was the first time I noticed it. Now I'll be curious to see if that's typical every morning.

 

Yes! I turned the lights on at 6:00am and fed them, and they had no black stripes and even the red rings around their eyes were faint. It was the first time I noticed it. Now I'll be curious to see if that's typical every morning.

Think it is. Lots of fish (tetras) do so !!!
No need to look bright in the night hahaha.

 

Thanks very much!