Don't know exactly what the issue is. Will he make it?

[Anastasia Lai]

I bought a beautiful blue crowntail fighting fish about 4 days ago. He was fine until last night when he seemed very lethargic and wouldn't eat. Overnight one of his eyes became very swollen and he can't swim very well. It became even more swollen during the day and I'm worried about how fast he seems to be deteriorating. He's just floating around at the top of the tank, not eating and not moving very much. He can't even float properly, he's often floating on the side. He's in a 20 litre tank (about 5.5 gallons) with a filter but I turned it off so I don't stress him out. The heater I had didn't work, but I thought he'd be fine as it's summer, but we're having a few cold days. His breathing, colour and fins seem fine but he's acting very sick. His eye had a whitish look to it so I added some fungal treatment to the water in hopes that it may help. The water is treated with dechlorinator and aquarium conditioning salts. I changed 50% of the water yesterday and 50% today. I washed his decorations with hot water today as I was worried they may have caused some infection (they were moved there from my other fish tank). Tonight's going to be a cold night, and he's barely moving as it is. Is there any chance that he'll make it through the night, and what else can I do to help him? (I can't get another heater until tomorrow).

He's swimming around a little more now, and I can see him better. His other eye is also swollen but not as much as the first. The scales on the top of his head look raised but the scales on his body are smooth.

[Anastasia Lai]

I don't know if the medication helped but he's not floating on his side anymore. He's staying the right way round fairly well, and he's just drifting around the top of the tank. He still doesn't seem to be able to swim as strongly as he should.

[Anastasia Lai]

I forgot to answer these:

Housing
What size is your tank? 5.5 g
What temperature is your tank? Around 70 degrees ( I know its cold D: )
Does your tank have a filter? Yes, but it's off.
Does your tank have an air stone or other type of aeration? No.
Is your tank heated? Not currently.
What tank mates does your betta fish live with? None

Food
What type of food do you feed your betta fish? Hikari Betta Bio-Gold Pellets
How often do you feed your betta fish? Four pellets, once a day.

Maintenance
How often do you perform a water change? Weekly, but currently I'm doing them daily
What percentage of the water do you change when you perform a water change? 50%
What type of additives do you add to the water when you perform a water change?
Dechlorinator, Conditioning Salts and Carbonate Hardness Powder.
Water Parameters: N/A don't have a testing kit.
Have you tested your water? If so, what are the following parameters?

Ammonia:
Nitrite:
Nitrate:
pH:
Hardness:
Alkalinity:

Symptoms and Treatment
How has your betta fish's appearance changed? He has popeye, one eye is fairly large and cloudy, the other is only bulging slightly. The scales on the top of his head are raised.
How has your betta fish's behavior changed? He's very lethargic, not eating (can't see the food?), he can't swim properly.
When did you start noticing the symptoms? Yesterday afternoon.
Have you started treating your fish? If so, how? I've given him a fungal treatment and changed the water.
Does your fish have any history of being ill? No.
How old is your fish (approximately)? I've only had him for 4 days.

[sainthogan]

First of all, cold water will cause lethargy and a whole bunch of other health issues. Start with getting a heater, as far as swimming funny and having popeye, you can use epsom salts. 1-3 teaspoons per gallon is ok. Start with a small amount pre-dissolved to get him used to it. Epsom salts will help pull out the swelling causing the popeye and possibly the swimming issue.