Unhappy Betta

Hi there - I've got rather an unhappy Betta at the moment.
 
There's a before shot and I'm just downloading a now shot from my camera, the before is from my phone and not great.
 
He's lost a lot of colour and some mass too, he just looks grey compared to his previous gorgeous blue.
 
Due a 20% water change tommorrow, he's in a 20L tank with sand, silk plants kept at 27degrees ish (right now its 27.2 degrees). Looking fan yesterday morning when I had time from work to spend time watching him other than dropping in a little food last night which it nibbled up. This evening - no interest in food at all.
 
He's all alone in the tank except for a few small snails which somehow made it across inside one of his decorations. The before shot has a plastic plant, but as suggested here I moved to silk.
 
Sorry - I'm not even sure of the gender ! But rather sad looking poor little one right now.
 
I've put in some general fish tonic and started the water treatment tonight so I can change first thing in the morning. But help / advice would be super welcome at this point. I'm going to go with algae / fungus treatment tomorrow morning as well unless someone tells me I'm being a doofus to do that.
 
 

you have a male
how long has the tank been up?
did you cycle? if so for how long?
what type of snails? sometimes some can be release chemicals and kill fish, then eat them etc etc.
what are you feeding him?

Hi Berry - I've added in a current shot which finally downloaded from my Canon (I had about 8gb worth to work through to get it as I hit download on auto pilot).
 
Thanks for confirming gender, had guessed / hoped that the bright colours were boys but didn't want to make a silly mistake.
 
1) Originally we had a 60L tank which we upgraded to 125L. When we did that we kept him in the 60L and looked into a smaller tank as the 125L came with two guppies
2) Bought a 20L All Pond Solutions tank, sansibar sand and used water from the existing tank into the new tank which I left for 3/4 days with some old media from our filter in it to circulate around. Then I took out about 1/3 of the water, added clean, heated to 27 degrees and moved him in. Then after a three days I found a crack on the inside of the tank, so I had it replaced. That was a week ago - I put new cleaned sand into the new body, added the heater etc and filter media over, then moved the water over and did a 1/3 water change at same time
3) The snails are the same as some of the ones in my main tank, all I can say without hunting a shot is that they are small and black - no issues with them in the other tank
4) I do a 20-25L change per week on my 125L and 6ish litres on this tank
5) He's being fed tetra tropical fish flakes right now, previously he was on lovefish tropical flakes
 
Lastly - thanks for posting

Did you ever test the water? Sometimes when adding mature media, it may not quite be enough for the amount you are dosing, so there still could be ammonia or nitrite in the tank.

It also looks like he has fin rot, too. This is sometimes because of ammonia, even more vital that you test your water. How long have you had him, by the way?

Had him : Six ish weeks
 
Fin Rot : Oh dear. I think I've something for that in my cupboard
 
Water Test : On the agenda for today, pre the water change. Will fill my vials (API Kit) and see what the outcomes are during course of today.

I would probably be inclined to do more than a 20% water change, more like 60-80% and replace with temp matched dechlorinated water.

I have my betta (who is almost similar to yours) in a cycled 22litre but he loves big water changes may help perk him up a bit.

You almost never have to treat fin rot with medication. Usually it can be improved with frequent water changes.

Hi all - thanks for your advice.
 
I did the suggested 60-80% heat matched water swap last night, however, as I was also due a change in the main tank I forgot to keep some water back for testing. Idiot - two siphons running at once, one charging, one emptying.
 
However, as of yesterday morning he was willing to take a little food. I did add a little / half dose of the fin rot treatment I have just to give him a bump along. I also shut down the pump / filter as he was seeming to struggle against the current. Since then he's been more active. Last night he was surface eating flakes too. Clearly had his fill as he nibble some then spat it out.
 
He's still hanging in there basically, I'm hopeful that with a few more days of eating he'll have some strength. Just worry about longer term side effects of being so thin / weak. I'm going to let the tank settle for a day or too and start the test logging on that tank like the larger one.

Is your pump still off? I would switch it back on but baffle it so its not so strong.
Some pumps you can adjust the flow, others you can put some filter sponge over the outlet.

I would be worried about your filter media bacteria dying off without a flow of water, and a build up of ammonia in his tank.