Please help my fish is dying one after one

[Gempk5]

You need to at least two more 50% water changes.
Your nitrate was 300+ ,so 50% water change gets you to 150+ nitrates...
Two more separate 50% changes should get you in the 40+ range...

I will do it today thank you for your advice

Can I start kanamycin after water change.?

 

[coralbandit]

Can I start kanamycin after water change.?

Yea that will be best.

 

[Gempk5]

do you guys think that internal bacteria or external

 

[coralbandit]

Columnaris can be both . You see the external effects of the bacteria but can't see the damage internally.
If besides the white patches your fish seem ok then possibly the infection is only external.
Hard to tell.
The link I posted "What I have learned about columnaris" tells you about the 4 recognized strains and their symptoms.
http://www.myaquariumclub.com/columnaris-and-what-i-have-learned...-11839118.html

 

[Angellove78]

I think they would have both. My opinion. But I'm not an expert...yet...

 

[V227]

IMO, the infection is the less lethal strain of Columnairis. His fish aren't dying overnight like they would with strain #1. Less lethal, probably not the correct term, more like "lingering death".
The outlook is still gloomy.

 

[Gempk5]

I start kanamycin direct to the water , so far it's 24 hour ago , on the pictures showing look like there's nothing Improvement so far , I will update every time, thanks guys for your opinion

New video

https://youtu.be/uMWAKUNwcKE

 

[Gempk5]

Its the second dose for kanamycin look like it doesn't work

 

[coralbandit]

Continue whole treatment and change water [as much as you can] when the directions say to.Most antibiotics can take 5-14 days to work completely.