Is this fin rot on my mandarin

[PeterEde]

How can I help him? Is it definitely not the angle of his body?

You say it eats everything. I feed mine via pipette brine shrimp every 2 days until it swims away full.
Mine looked well under nourished when I got her. She's now a plump little girl.
I've had mine 6 months an never seen her feed on any food other than brine I give or pods I put in the tank.

 

[Phoerut]

So I took these this morning, does he still look unhealthy because I’m worried now but i really didn’t think his weight was an issue? I have however noticed that that my bangii cardinal is being very territorial and a bit aggressive towards the other tank members, is there anything I can do to reduce this? It used to be the most peaceful fish but now he’s looking a bit more mature he’s being pretty mean

 

[Rmckoy]

So I took these this morning, does he still look unhealthy because I’m worried now but i really didn’t think his weight was an issue? I have however noticed that that my bangii cardinal is being very territorial and a bit aggressive towards the other tank members, is there anything I can do to reduce this? It used to be the most peaceful fish but now he’s looking a bit more mature he’s being pretty mean

How long has the system been running ?

looks very new and clean

 

[Jay Hemdal Verified Community Expert]

So I took these this morning, does he still look unhealthy because I’m worried now but i really didn’t think his weight was an issue? I have however noticed that that my bangii cardinal is being very territorial and a bit aggressive towards the other tank members, is there anything I can do to reduce this? It used to be the most peaceful fish but now he’s looking a bit more mature he’s being pretty mean

These photos do not make the fish seem as thin as the first ones did. That is a major drawback to only having photos to work from. I thought I could distinctly see the body ridge on one of the first photos - that is a sign of emaciation in this species. I do not see that here.

This is all akin to me holding my chin up when getting my photo taken so that my double chin is less pronounced (grin).

Jay