Sick And Lethargic Betta

[ReiRei]

Hey folks.
 
Recently, one of my fighters has begun to refuse any food. Seeming more interested in my finger, than the food in front of him. He's also swimming around the tank like he's desperately trying to find something to rest on, when he does find something ideal, he'll sit there for a good hour or so. He's one of two fighters I bought from someone local to me, and the first one died after becoming like this. She was in a completely different tank, with community fish, and just became lethargic all of a sudden and died for seemingly no reason.
 
The water levels in the tank are fine, I've just checked them. I water change the tank twice a week. It's a 30 litre, with amazon sword plants and ornaments. PLEASE NOTE: I had a massive infestation of hair algae all over the amazons, which I removed yesterday, could this be the cause at all?
 
I'd post a picture, but there arn't any physical signs of whats happening. He's usually a very active fish, to the point where I'd yet to see him sleep at night.

 

[ReiRei]

Could really use some help. He's worse today, not moving much at all. I've added Epsom salt.

 

[ReiRei]

Never mind. He passed away.

 

[Ninjouzata]

So sorry for your loss! Wish I knew more about bettas and could help figure out what was wrong..

 

[AlitaConejita]

sorry Is this the betta whose tail fin would disappear, re-grow, and then disappear again?

 

[ReiRei]

It looks like it was a nasty parasite that did it. No, this was Sebastian, one of my red fighters. ):

 

[Wildbetta]

So so sorry to hear about this.  SIP Sebastian.  

          It is hard to treat something like this so don't beat yourself up over it.  At least you provided a good home for him. 

 

[ReiRei]

Yeah, there weren't any symptoms until two days before - didn't give me time to experiment much. I  just assumed swim bladder, and thus treated for that. I would NEVER have considered parasites, as he didn't show the normal reaction to it. Its only when I think back to the other one, who died the same way, that I bought alongside him that I joined the dots.
 
Woke up this morning, and Morgan - the devil - had a bloated stomach. Immediatly it was like: Anyone ELSE want to do anything?! But I got back tonight, and after a pea this morning, he's fine.
 
In regards to this empty tank, I've secured a Grade A Mustard Gas Halfmoon Betta. Blue and Yellow. So looking forward to that in a week.