Bichir tail. Stress? Aggression? Fin rot?

[OakBichir]

Have you tested your water?

Yes

If yes, what is your ammonia?

.25

If yes, what is your nitrite?

0

If yes, what is your nitrate?

40+

If I did not test my water...

...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?

41-50%

How frequently do you change your water?

Every two weeks

If I do not change my water...

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

As you can see in the photo I had him in a tank a year ago and moved him into a different one. I noticed the end of his tail is whiter and shorter. I found an old photo from a year ago and its quite a bit different.

 

[tlindsey]

As you can see in the photo I had him in a tank a year ago and moved him into a different one. I noticed the end of his tail is whiter and shorter. I found an old photo from a year ago and its quite a bit different.

View attachment 1526526

View attachment 1526525

Was the bichir the only fish in the aquarium a year ago?
It's possible that the bichir is being nipped by fish in 2nd pic.

 

[OakBichir]

The first tank he was eating all the fish. He was with another bichir, South American cichlid, Bristol nose, and he was eating all the schooling danios. He is now with a texas cichlid, bristlenose, bichir, and synodontis catfish.

 

[tlindsey]

The first tank he was eating all the fish. He was with another bichir, South American cichlid, Bristol nose, and he was eating all the schooling danios. He is now with a texas cichlid, bristlenose, bichir, and synodontis catfish.

It may possibly be one of the cichlids nipping it's fin when the bichir gets in their territory.