Oscar fins blackening

[safwansidd]

Have you tested your water?

Yes

If I did not test my water...

1. ...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.

Do you do water changes?

Yes

What percentage of water do you change?

31-40%

How frequently do you change your water?

Every week

If I do not change my water...

1. ...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.

Hi guys, I have three chilli red tiger oscars all are the same size 4 inches approx and lately I noticed that edges of their fins are turning darker/black but it wasn't like this when I first got them. They are healthy and eating aggressively is this fins darkening common in oscars or any water quality issue I should be worried about?

 

[Deadeye]

Pics?
Sounds like natural color change as they grow up.

 

[safwansidd]

Pics?
Sounds like natural color change as they grow up.

Look at the fin outline there's a layer of black. I thought the same for min that it must be natural given they're healthy and eating but again let me know your opinion.

 

[Deadeye]

Looks fine. It does seem like normal patterning, especially how it appears the same way on all of them. Possible stress, I noticed some black scales. It doesn’t look like disease, but you never know. I would keep an eye on it either way.

 

[Jexnell]

It's normal for Oscar's colors to change while growing out. The fact that the black is showing up tells you they are Lutinos and not albino.

What I started with

Somewhere in the middle

Finally the end rewards

We can't say if the black will stay or grow out, each fish genes are slightly different. Just have to grow it out and hope for the best.