Fin rot in betta- help

[BAT]

Hi Nerms,

my betta has fin rot (I think). Not sure cause. I have been checking the water parameters with AC test strips and all parameters were low to zero. The tank had cycled bc I had a nitrite spike at end of June that passed. I kept 1 tbsp to 1 gallon salt in the water with the fish.
 

I didn’t change the water for 3 wks bc the test strips were negative. Then I changed and took salt concentration down. 

Over past 2 weeks I have noticed his lower fin getting more ragged. I started ichX and  kanaplex Saturday. And I restarted the salt to move the concentration back up. I have been changing water every two days. Added IAL. He made bubble nests with it. 

Today nitrate was 20; nitrite and ammonia were 0. Before water change. 
 

see pic 

he is eating well but seems frenetic  which is the sign I use to notice something is off. I started treatment when I saw a little erosion and he was frenetic when I come up to tank  

 

Do you think there was a nitrate spike that I missed?

anything else to do?

 

Edited July 26, 2022 by BAT

[Barbvday]

Kanaplex is a good idea and maybe Maracyn (erythromycin) to make sure you have all the bases covered.

There’s  a lot of variables that can affect the water quality of a fish tank. Not sure what you mean by “tests were negative”. Do you mean everything was 0? That’s odd for a cycled tank since you should have some nitrates unless it’s heavily planted. Also what is the PH?
 

[BAT]

the recent test strips were negative - meaning 0 nitrate and 0 nitrite.  now I wonder if they were accurate.  has anyone had that happen?

but I know that there had been nitrite in the water weeks ago (by both test strips and the API kit)