Help! Lethargic heavy breathing Betta

[Anil]

I do see problems with my Betta. Initially started with fin rot and now its all the time at the bottom of the tank with heavy breathing. It swims up to eat and goes down. I see one of the fin is pulling the Betta to side making it to lie flat.
{5 liter Tank, I use de-chlorinated water, a heater, UV filter}
I am using "aquarium salt + Melafix + Pimafix" for a week now but not much improvement.

YouTube videos link:

 

[Essjay]

Do you mean 5 litres or 5 gallons? 5 litres is much too small for a betta.
How powerful is the filter, does it push him round the tank?
How long have you had the betta?
Did you cycle the tank before putting him in there? By cycling, I mean did you add ammonia?
What are the levels of ammonia and nitrite in the tank water?
How often do you do water changes, and how much?

Live plants in the tank would help. As there is no substrate (gravel or sand on the bottom) you could use floating plants or plants such as anubias or Java fern attached to an ornament; or even moss balls.

And please stop using Melafix and Pimafix. These contain aromatic oils which interfere with a betta's labyrinth organ

 

[Anil]

Do you mean 5 litres or 5 gallons? 5 litres is much too small for a betta.
How powerful is the filter, does it push him round the tank?
How long have you had the betta?
Did you cycle the tank before putting him in there? By cycling, I mean did you add ammonia?
What are the levels of ammonia and nitrite in the tank water?
How often do you do water changes, and how much?

Live plants in the tank would help. As there is no substrate (gravel or sand on the bottom) you could use floating plants or plants such as anubias or Java fern attached to an ornament; or even moss balls.

And please stop using Melafix and Pimafix. These contain aromatic oils which interfere with a betta's labyrinth organ

I use ecoqube (https://getecoqube.com/products/ecoqube-c-basic) which stores around 2.5 gallon of water.
Its been 4 months with this Betta and yes I did the full tank water cycle before putting to tank.
I normally change the water once a month however now with the problems I am changing 25% water change every week.
there is filter UV with carbon at the back of the tank. Also there is a live plant which runs on the back of tank however I am not too sure how healthy that plant is (hardly I ever it growing).

 

[FishGuest5123]

Do a 75% water change daily for a week and see if that helps. Then, do a 75% once a week. Your water changes are too small and need to be done weekly. Actually, in a tank that small I would change water 2 x’s a week. Is it heated and filtered?

 

[Essjay]

He said it has a heater and a UV filter.

The UV filter - is this a filter which also has UV or is it just a UV light?

 

[Anil]

it says UV LED sterilizer. Earlier I used sand at the bottom however removed later thinking sand surface may further damage the fin rots.

 

[Essjay]

Does the tank have a proper filter; that is one with sponges or cartridges, somewhere for the beneficial bacteria to live? A UV light on its own is not a filter, just a UV light.
Another question, if I may - the UV light, does it shine directly into the tank or is there a sort of sleeve around the light and the water flows between the sleeve and the light?

What are the levels of ammonia and nitrite? These are more likely to cause fin rot than the sand.

Fish excrete ammonia. There is a type of bacteria which 'eats' ammonia and turns it into nitrite. Another species of bacteria 'eats' nitrite and turns it into nitrate. Both ammonia and nitrite are poisonous to fish. The bacteria which eat them live in the media inside a filter (sponge, cartridges etc) and in the sand or gravel on the bottom of the tank. Without these bacteria, ammonia and nitrite build up and poison the fish. Because they are weakened by the poisons they get infections much more easily.
We need to know if you have a proper filter, not just a UV light, and what the levels of ammonia and nitrite are in the tank water. Once we know the answers we'll be able to help you better.

 

[Anil]

Yes it has the filter with UV attached to it. It also has the sponge and carbon filter.

Thanks for the suggestions.. I will test the ammonia & nitrite level and let u know.