Betta is at bottom of tank

[RezKat]

Hi was wondering if anyone can help. I have a 20 litre tank, temp at 24C with filter and pump. My tank has a Albino catfish, Platy and a Betta. The betta recently has been on the ground and not moving alot, iv noticed over the past few weeks his tail looked shredded now it is short, his fins look smaller too. the petshop said i was to put him in a jar till he's better. I feel that's kinda cruel or is that normal?

 

[thrujenseyes]

I'm going to give you bad news.
That tank is way too small. There should only be one beta or shrimp only in there.
Definitely not a platy and def not a catfish.
And DEFINITELY not those three together. Not just because of size but they should NOT be together.
I would rehome the platy and the catfish and try to save your beta.
Is this tank cycled? That could be yet another issue.

 

[RezKat]

I'm going to give you bad news.
That tank is way too small. There should only be one beta or shrimp only in there.
Definitely not a platy and def not a catfish.
And DEFINITELY not those three together. Not just because of size but they should NOT be together.
I would rehome the platy and the catfish and try to save your beta.
Is this tank cycled? That could be yet another issue.

This is my daughter's first tank and we initially bought the betta, a guppy and a platy all from same shop, after reading online i saw it was a bad idea to have the guppy in with betta but the betta killed him. i dont know alot about keeping fish. i had the tank filled with all apliances in it for about a month before we got the fish and had to take a sample of the water to the pet store. he told us everything was fine. after the guppy was killed i read the catfish and betta would be fine together and everthing was fine for weeks, but iv noticed the betta tail is tiny now and his fins look smaller. the pet shop told me to put him in a glass jar changing his water twice a day till hes better

 

[RezKat]

I'm going to give you bad news.
That tank is way too small. There should only be one beta or shrimp only in there.
Definitely not a platy and def not a catfish.
And DEFINITELY not those three together. Not just because of size but they should NOT be together.
I would rehome the platy and the catfish and try to save your beta.
Is this tank cycled? That could be yet another issue.

im in uk so 20 litres = 4.4 gallons

 

[thrujenseyes]

This is my daughter's first tank and we initially bought the betta, a guppy and a platy all from same shop, after reading online i saw it was a bad idea to have the guppy in with betta but the betta killed him. i dont know alot about keeping fish. i had the tank filled with all apliances in it for about a month before we got the fish and had to take a sample of the water to the pet store. he told us everything was fine. after the guppy was killed i read the catfish and betta would be fine together and everthing was fine for weeks, but iv noticed the betta tail is tiny now and his fins look smaller. the pet shop told me to put him in a glass jar changing his water twice a day till hes better

Unfortunately pet shops are full of terrible advice. Most just want to sell you whatever they can.
There are a few exceptions but honestly not many.
I commend you for reading up on it and coming here to find answers.
Letting you tank "sit" for a month won't do anything to prepare it for inhabitants.
The fish store telling you the water is "fine" really means nothing.
Unless they tell you what all of your parameters are (ph, gh, kh, chlorine, ammonia, nitrite and nitrate) we don't know ....it's a must for us to have our own test kits.
But....
You must first cycle the tank.
There is a wonderful article on this forum about it:
http://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/

I too have a tiny little tank (6 gallon) and only keep (at most) 5 teeeeeeny fish (endlers, less than inch) and two shrimp and one snail. I opted for this instead of a beta because I wanted a few different inhabitants instead of a single fish. Beta should be solitary. They do not enjoy "having friends".
Yours is in trouble and I'd love to see you remove the other two and leave him in there to heal on his own.
It won't end well for any of them if you leave them all together.

Sorry to give you such bummer news, but it will save you much heartache if you read up and cycle the tank and go from there.

Unfortunately the only advice I can give you right now is to rehome the other two, keep the beta and put in something else while you're tank cycles and do a lot of water changes to keep him healthy.

 

[NickAu]

The pet shop lied to you, I would go back and complain create a scene especially if there are other customers in the store, Let the other customers know they misled you.

24 is also a bit cool for a betta.
How strong is the current in the tank.
How often do you change water.
How much water do you change.
What water treatment do you use.

Keep the betta in the tank ( rehome any other fish ) you are going to be doing a fish in cycle and that means daily water changes and testing.

Do you have a water test kit?