Early signs of fin rot?

[Gideyon]

I examine my betta's fins every night. 

 I know one of the early signs of fin rot are brown jagged edges.  But what about just jagged edges without the color?

He's a very active fish. Roams the full 10g tank. I've never seen him nip. But not sure if he does.   

I tested the water 2 days ago

pH 7.4

Ammonia 0.003

Nitrite 0

Nitrate 5.  

40% water change yesterday with gravel vac. I've been raising the temp on the heater gradually.  It just can't hit 78 for some reason (yes, it's a 50w).   It stays around 75 or a little above.   There's one IAL inside, but my polypad seems to be capturing all the tannins. 

What does it look like to y'all?  

 

This was about 8 hours after the water change.  Didn't notice it prior. 

Edited March 26, 2021 by Gideyon
Noting when picture was taken

[FrozenFins]

Can you make the picture bigger and zoom in on the places where you think finrot is starting?
From the picture you took it does not look like earl signs of finrot. Heres what mine looked when it had early signs of finrot:

[Gideyon]

3 minutes ago, JamesB said:

Can you make the picture bigger and zoom in on the places where you think finrot is starting?

 

[Daniel]

Looks normal to me,  I wouldn't be concerned.

[lefty o]

1 hour ago, Daniel said:

Looks normal to me,  I wouldn't be concerned.

agree.