Betta being lethargic, and not spreading his fins

[omyard]

So my little blue betta has been hanging out towards the bottom of his tank the last few days. I didn't think anything of it because he and my other betta (in another tank) do that from time to time. Last night I noticed when I went to feed him that he wasn't moving very well and had a hard time swimming. It looks as if he can't or won't spread his fins and just slowly sinks back down after trying to swim up.

I looked online last night at the diseases and didn't see anything that looked like what was going on with him.

The only change in his aquarium is that I recently started using c02 booster for the plants in his tank.

I have another betta in a separate tank and they have identical plant set ups and the other one is swimming around like he always does. So there must be something effecting just the sick one.

He's not looking too good, but I hope I can do something to save him.

Housing
What size is your tank? 5gal
What temperature is your tank? Near 80
Does your tank have a filter? Yes
Does your tank have an air stone or other type of aeration? No
Is your tank heated? Yes
What tank mates does your betta fish live with? Just some plants, moss ball, wisteria, amazon sword

Food
What type of food do you feed your betta fish? small, normal pellets
How often do you feed your betta fish? daily

Maintenance
How often do you perform a water change? 2 weeks
What percentage of the water do you change when you perform a water change? 20%
What type of additives do you add to the water when you perform a water change? Tap water conditioner

Water Parameters:
Have you tested your water? If so, what are the following parameters? No

Symptoms and Treatment
How has your betta fish's appearance changed? Outside of his fins not expanding? No.
How has your betta fish's behavior changed? Yes, he's been more lethargic than normal.
When did you start noticing the symptoms? A few days ago.
Have you started treating your fish? If so, how? No.
Does your fish have any history of being ill? No.
How old is your fish (approximately)? I bought him at the pet store a year ago.

[ChoclateBetta]

I would do more water changes and add more decorations.

[omyard]

Originally Posted by ChoclateBetta

I would do more water changes and add more decorations.

Water changes sure, but his tank is pretty full. With the plants I also have a big pirate cave for him to swim into that he loves.

He's looking pretty close to being a goner right now.

[snazy]

What CO2 booster are you dosing? How much and how often? With liquid carbon be careful not to pour it over the fish as I killed one myself like that. Put it in slowly into the filter flow so it gets spread around quickly.
Have you added anything else to his tank recently, new plants or decoration that may have brought a disease?

I would do at least 50% water change with dechlorinated/temperature matched tap water, even a bigger one is better, just make sure you add the water slowly to let the fish adjust to it. If you can test for ammonia and nitrItes just in case would be good. Also, test the Ph, in case it has crashed(called old tank syndrome)

[ChoclateBetta]

I agree.

[omyard]

Originally Posted by snazy

What CO2 booster are you dosing? How much and how often? With liquid carbon be careful not to pour it over the fish as I killed one myself like that. Put it in slowly into the filter flow so it gets spread around quickly.
Have you added anything else to his tank recently, new plants or decoration that may have brought a disease?

I would do at least 50% water change with dechlorinated/temperature matched tap water, even a bigger one is better, just make sure you add the water slowly to let the fish adjust to it. If you can test for ammonia and nitrItes just in case would be good. Also, test the Ph, in case it has crashed(called old tank syndrome)

I added some of the plants and the moss ball, but those were a month ago.

Not sure which brand the CO2 booster it is since it's at home. I got it at Petsmart and it's in a white bottle.

I'll do a water 50% water change when I get home.

[ChoclateBetta]

That will help wish you the best.

[snazy]

Some parasites, bacteria may take a month until the fish shows signs of infection too so the plants may have brought something, hopefully not.

I would do an even larger water change, pouring back the dechlorinated water slowly to let the fish adjust, this way you'll be sure you've removed most of the possible problem if it's something in the water.