Usually active betta suddenly lethargic

PLEASE HELP! I'm providing the details of my fish below and have explained the situation in detail afterwards.
Tank

What is the water volume of the tank? - 7 gallons
How long has the tank been running? -1.5 years, but went through a 100% water change about a week ago because we moved states
Does it have a filter? - Yes
Does it have a heater? - Yes
What is the water temperature? - 77-78 degrees Fahrenheit
What is the entire stocking of this tank? (Please list all fish and inverts.) - one male betta

Maintenance
How often do you change the water? - once every 2-3 weeks
How much of the water do you change? - about 35%
What do you use to treat your water? - Stress Coat and API aquarium salt
Do you vacuum the substrate or just the water? - the substrate

*Parameters - Very Important
Did you cycle your tank before adding fish? - Yes
What do you use to test the water? - API Master Test Kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.

Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: 5 ppm
pH: 6.8

Feeding
How often do you feed your fish? - every other day
How much do you feed your fish? - 4 pellets
What brand of food do you feed your fish? - Betta Buffet
Do you feed frozen or freeze-dried foods? - No

Illness & Symptoms
How long have you had this fish? - one year and 7 months
How long ago did you first notice these symptoms? - this morning
In a few words, can you explain the symptoms? - lethargic, mostly hanging around the bottom corner of the tank. swims to the surface once in a while for air and swims erratically/darting before settling back near the bottom again. responds to human interaction and goes up for food but otherwise pretty listless.
Have you started any treatment for the illness? - changed 50% of the water
Was your fish physically ill or injured upon purchase? - No
How has its behavior and appearance changed, if at all? - fins seem clamped, is overall lethargic and uninterested in his environment

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

Hello! After panicking for hours, I've finally decided to make a post about my suddenly lethargic betta. I've had him for a little over a year and a half and he is always very active, interacts well with people and loves exploring his tank and swimming in and out of the decorations in the tank. However, I'm not sure if this has been a problem for a few days or not because I only started noticing his odd behavior this morning. He spends nearly the whole day near the bottom of the tank, not moving at all but breathing normally. If you go near the tank, he still takes some time to notice but he will rapidly swim to the top for air and erratically swim around for about 30 seconds before settling back near the bottom, behind the heater or on top of the central decoration. The first thing I thought of doing was a 50% water change, and he has had only slight improvements with his movement but otherwise still pretty listless. I purchased the API Master Test Kit to check the water parameters after the water change (which might have impacted the test results?) and everything seems normal, and he is also responding well to food as he comes up immediately when he thinks I'm going to feed him and gets ready to accept the pellets. I'm not sure where to go from here as he's always been a happy, active little betta and the lethargy and listlessness that started this morning is very abnormal for him. Any help would be gladly appreciated, this is the longest I've ever kept a betta and don't want to see him go for something I can fix. I've attached a few pictures of the tank as well as how he's laying around the top of his decoration in case those might help. Thank you!

 

I'm really sorry to hear your little guy isn't well OK, so
Did you bring any of his old tank water with you to acclimate him to the new water? He might have a little PH shock if you didn't.

And I see you add aquarium salt to his tank?
I would stop doing that. Aquarium salt doesn't evaporate, so builds up inside the tank so it can be overdosed by accident, because of the build up inside the aquarium.
Aquarium salt should only be used in a quarantine tank when your fish is unwell. Its not good for freshwater fish longterm.

His temperature is ever so slightly off for him too. You might want to get it up to 80 , in my personal opinion, this is an optimum temperature for bettas
I really hope this is helpful

 

I'm really sorry to hear your little guy isn't well OK, so
Did you bring any of his old tank water with you to acclimate him to the new water? He might have a little PH shock if you didn't.

And I see you add aquarium salt to his tank?
I would stop doing that. Aquarium salt doesn't evaporate, so builds up inside the tank so it can be overdosed by accident, because of the build up inside the aquarium.
Aquarium salt should only be used in a quarantine tank when your fish is unwell. Its not good for freshwater fish longterm.

His temperature is ever so slightly off for him too. You might want to get it up to 80 , in my personal opinion, this is an optimum temperature for bettas
I really hope this is helpful

I was only able to save about half a gallon of his old tank water, the rest of which I had to use fresh water to fill up. If he does have pH shock, what is the best way to go about treating it? This is the first time I've used a reliable water test kit as I used the test strips in the past and they weren't always accurate.

I had been adding 1 tablespoon of aquarium salt with his water changes, but if it isn't good for him I'll stop doing that from now on. I'm not sure whether I can raise the temperature or not because it is a set heater that keeps the temperature at around 77-78 degrees Fahrenheit.

Thank you for your response, any information on pH shock and how to go about treating it would be extremely helpful.

 

I was only able to save about half a gallon of his old tank water, the rest of which I had to use fresh water to fill up. If he does have pH shock, what is the best way to go about treating it? This is the first time I've used a reliable water test kit as I used the test strips in the past and they weren't always accurate.

I had been adding 1 tablespoon of aquarium salt with his water changes, but if it isn't good for him I'll stop doing that from now on. I'm not sure whether I can raise the temperature or not because it is a set heater that keeps the temperature at around 77-78 degrees Fahrenheit.

Thank you for your response, any information on pH shock and how to go about treating it would be extremely helpful.

Aw, you're most welcome!
I know how upsetting these things are.

I just re-read your post and also noticed your water change schedule. Really , you want to be doing 25% every week.
I personally do 50% weekly for my tanks .
The salt actually seems to me, to be the problem. That is a lot of salt. Bear in mind, every time you add it, it leaves residue on the silicone and decorations.
So when you add another spoon, you're adding to the residue and thus overdosing over time.
I have a bare quarantine tank, that I treat fish with aquarium salt. It gets thoroughly cleaned after use to remove it, as it can be dangerous if not dosed accurately.

I'd up your water changes to try and remove it.
Maybe 25-50% daily and stop using salt.
Your tank is cycled according to your results so thats not the problem.
Often, frequent water changes are the best cure.
plants don't get along wit salt either by the way.
So, they will also improve and grow better

As for the temperature, If you can? I'd purchase a heater with a thermostat and adjustable temperature. Far more accurate than pre-set heaters.
Bettas become lethargic when they get a Little chilly.

I really hope he improves.
I have an older betta that's exhibiting similar behaviour. But he is just an old man.

 

Aw, you're most welcome!
I know how upsetting these things are.

I just re-read your post and also noticed your water change schedule. Really , you want to be doing 25% every week.
I personally do 50% weekly for my tanks .
The salt actually seems to me, to be the problem. That is a lot of salt. Bear in mind, every time you add it, it leaves residue on the silicone and decorations.
So when you add another spoon, you're adding to the residue and thus overdosing over time.
I have a bare quarantine tank, that I treat fish with aquarium salt. It gets thoroughly cleaned after use to remove it, as it can be dangerous if not dosed accurately.

I'd up your water changes to try and remove it.
Maybe 25-50% daily and stop using salt.
Your tank is cycled according to your results so thats not the problem.
Often, frequent water changes are the best cure.
plants don't get along wit salt either by the way.
So, they will also improve and grow better

As for the temperature, If you can? I'd purchase a heater with a thermostat and adjustable temperature. Far more accurate than pre-set heaters.
Bettas become lethargic when they get a Little chilly.

I really hope he improves.
I have an older betta that's exhibiting similar behaviour. But he is just an old man.

Sorry for so many replies, I just want to be 100% sure I know what I'm doing from here on out. Okay, so do you think that 25-50% water changes daily, without salt, will restore my betta's energy? I am having trouble finding any other issue as all of the water parameters seem to be ideal. I will look into purchasing a better heater as well to increase the water temperature to around 80 degrees. I did a water change earlier today with salt but I'll stop using that from now on and keep monitoring him. Besides that, is there anything else I should do for him?
Again, thank you for your time and expertise.

 

Oh, dont worry about that! Im happy to help.
Yes, first step would be the water changes without salt. Daily 25-50% should help him.

I'd feed him well to improve his immune system too. Vary his diet a little. Maybe buy some frozen brine shrimp, blood worms, daphnia etc. All of my bettas get a frozen meal once a week
If the water changes don't seem to have an affect.
I am happy to help further!
But I really do feel it's the salt. Bettas are not brackish or salt water so it really isn't good for them.
The acurate heater will be much better for him.

I wish you the best of luck, and like I said, you're welcome to come back if you have any issues

 

Oh, dont worry about that! Im happy to help.
Yes, first step would be the water changes without salt. Daily 25-50% should help him.

I'd feed him well to improve his immune system too. Vary his diet a little. Maybe buy some frozen brine shrimp, blood worms, daphnia etc. All of my bettas get a frozen meal once a week
If the water changes don't seem to have an affect.
I am happy to help further!
But I really do feel it's the salt. Bettas are not brackish or salt water so it really isn't good for them.
The acurate heater will be much better for him.

I wish you the best of luck, and like I said, you're welcome to come back if you have any issues

Hello! I know it has been some time since I last messaged you, but my betta fish is exhibiting the same behavior again as described in the original post except he prefers to lay on the substrate of the tank and only darts up to get oxygen from the surface. He is still eating normally and I haven't been adding salt during water changes so I'm confused as to why this happened again. His breathing is a little heavier than normal when he is laying on the bottom of the tank and it takes him a lot of effort to swim up to the surface. I have been changing around 35% of his water every other day for the past 4 days but he does not seem to be getting any better. Do you have any advice on what I should do next?

 

How old is he?

 

How old is he?

I bought him in January 2019, so in two months I would have him for two years. If it helps, everytime he swims to the surface he seems to float back down almost immediately and in really awkward positions, especially sideways or even sometimes headfirst. His fins also seem clamped and he's breathing heavily, but he still has an appetite. The water temperature is currently 77 degrees Fahrenheit.

 

I bought him in January 2019, so in two months I would have him for two years. If it helps, everytime he swims to the surface he seems to float back down almost immediately and in really awkward positions, especially sideways or even sometimes headfirst. His fins also seem clamped and he's breathing heavily, but he still has an appetite. The water temperature is currently 77 degrees Fahrenheit.

Possibly swim bladder...

 

Thank you all for your help these past few months, but sadly my fish passed away yesterday evening. I still appreciate all the help.