This is basically what he does now all the time. Little to no activity :-(

 

That's a bubble nest he's building. The little to no activity is what a lot of mature males do, a lot of times because their fins start to get big and heavy and weigh them down. I would start by removing that huge rock house thing and putting in some surface cover, floating plants, for instance, and maybe a much smaller cave, maybe a smallish ceramic coffee cup laid on it's side. That will give him more room to maneuver and he'll get a bit more active. Also, put a sheet of construction paper between the tanks so they can't see each other all the time and just remove it for 5 to 10 minutes a day. He'll get some excersize that way, he's too used to seeing the other bettas.

 

Witchipoo thanks for the response. The substance that looks like bubbles in the photos is the humidity from the tank unfortunately. I thought it could've been bubbled nesting too until I took a closer look yesterday. I think whats conceding me the most is the twitchy/erratic swimming movement, and the fact that he doesn't seem to be able to stay at the bottom of the tank he just floats back up. As for the rock thing, yea not my smartest decision. I ordered a smaller more adequate piece of decor but until it arrives I didn't want to leave him with nowhere to hide.

 

Did you match the tank water temp to what he is used to? Sudden temp changes can make them kind of shocky. Also, if you could fill out the care questionnaire in the sticky it would help us a lot to figure out what is going on so we can help you.
I would find the link and post it, but I'm using a crappy little phone and.can't get it to do stuff that complicated, it's a stupidphone, not a smartphone. :/

 

Here you go Witchipoo! Sorry I'm new to this website and didn't know this was necessary.

Housing:
How many gallons is your tank? 3/4 gallon
Does it have a filter? Yes
Does it have a heater? Yes
What temperature is your tank? 77 degrees
Does your tank have an air stone or other type of aeration? No
Does your Betta have tank mates? What kind? No

Food:
What food brand do you use? Aqueon
Do you feed flakes or pellets? Pellets
Freeze-dried?
How often do you feed your Betta? How much? 2 pellets every morning 6 days a week. I skip sundays to help rid any back up they may have.

Maintenance:
Before your Betta became ill how often did you perform a water change? 50% every few days. Complete water change once a month
What percentage of water did you change? See above
Do you vacuum the substrate or just dip out water? Vacuum
What additives do you use? None

Water Parameters:
What are your water parameters? Please give exact numbers. If tested by pet store please get exact numbers. "Fine" or "Safe" won't help us help you.

Ammonia: UNK
Nitrite: 1
Nitrate: 4
pH: 7.5
Hardness (GH): 180
Alkalinity (KH): Unclear reading between 40/80

Symptoms and Treatment:
When did you first notice the symptoms? 2 days ago
How has your Betta’s appearance changed? Im not sure if it was always like that but maybe some minor swelling in the abdomen just behind the gills
How has your Betta’s behavior changed? Non Active. When he does move his swimming is a twitchy erratic movement. Always hiding or pressing against something. Cannot seem to be able to stay at the bottom of the tank, floats up.
Is your Betta still eating? Yesterday he ate 2 pellets with no hesitation
Have you started treating your Betta? If so, how? Don't know how
Does your Betta have any history of being ill? No he was the most active healthy of my 4 Betta's
How long have you owned your Betta? Was he or she a rescue? Costa was purchased about 2.5 weeks ago from a local pet store

 

Ok, it sounds like it could be swim bladder disease, SBD, which is totally treatable.
I found this course of treatment in the disease section, my memory is shot, I have to look everything up.
Swim Bladder Disease (SBD)/Bloat
•Symptoms: Betta has trouble swimming, maybe he can’t stay upright and can only swim on his side.
•Treatment: This is not a contagious or fatal illness. If it isn’t congenital (aka a condition that he/she has had since birth), then it is caused by over feeding or feeding the wrong foods. Bettas will typically recover after a day or two of Epsom Salt treatments (1-2tsp/gal) and fasting. You can help prevent a reoccurrence by switching to a better pellet food, feeding less and offering a more varied diet. To make it easier for the betta to eat and breath, you can make the water shallower. You can offer him/her frozen daphnia (sold at Petsmart) as daphnia will help him/her pass stool. DO NOT FEED THEM PEAS.

Also, type of food is important, get your Betta friends some new life spectrum pellets or Omega One. Look for foods that don't have fillers in the first three ingredients, things like corn, wheat and wheat gluten are bad for carnivores, which is what bettas are.
Do you use a water conditioner to remove chlorine, chloramine and heavy metals?
Seachem Prime is recommended, it takes two drops per gallon and locks up ammonia as well.

I hope this helps your little guy. Keep us updated!

 

Ok so what appeared to be just one fish with swim bladder is now 2. I only have one hospital tank so I have Cota who has been sick the longest in there. I have the temperature at 80 degrees. He was on a 2 day fast and I fed him some daphnia this afternoon. His behavior has not changed but I'm hoping it will improve in the next day or so. I noticed that he has an awkward curve to his spine at times so I'm hoping its nothing more serious that just swim bladder. I haven't tried the epsom sale treatment for fear of doing it wrong and harming him even more. If there is any other help or suggestions anyone can make, please let me know via forum reply or private message.