Help my new betta is not doing well

[Connerstunt]

i just got a desk aquarium thats 4 gallons. it has a air stone some live plants i set it up about 3 days ago..

i added a betta fish yesterday he looked happy but when i woke up this morning he didnt look good. he stayed at the top of the tank. now its 5 pm and hes mainly at the bottom. looks like he has fuzz on him and his tail looks frayed..

when i got him at the store he didnt look like that..

the tank is at 75-76 degrees

im not sure whats wrong?

is it my water? i used tap water and added betta bowl plus. (i added the dechlor and about 10 minutes later i added the fish.

someone said i need spring water.

please help i dont know what to do and dont want to have him die. its been a while since i had a aquarium.

[Larkspur]

OH NO! Well I'm not as much of an expert as some of the other people on this site but if he's covered in white fuzz it could be ich some sort of fungus? Maybe try some anti fungus medication? but until you know for sure put some epsom or aquarium salt in the water. I believe it is one tablespoon per 5g of water. I hope your fish gets better!! D: