I Think I Stressed Out My Betta. He Has Been Hiding In A Cave For 6+ H

[Inchyally]

Hi, this is my first post on this forum in about eight years. My profile picture is a drawing of my old Severum which died of ich three years ago...
 
 
I had a Betta in a 5g tank. I had him for about two months - I had another betta who died at four years old. Anyway, the HOOD of the tank broke. Lightbulbs no longer worked, and it was a hexagon tank so I couldn't just replace the hood. Anyway, I decided to upgrade - I bought a 20 Long. I set it up, and ran my 5g filter in it, PLUS added some gravel/decorations from both my 5G and my 55G. I had to remove the 5G filter after a day as I couldn't fit the 5G filter and the 20G filter. I assumed that this all would have helped instantly cycle the tank (I got told that by people on reddit) but no... there was an ammonia spike. My betta became lethargic. He floated in the corner of the tank for a few hours, not even moving his fins.
 
 
I, as an emergency measure to get him out of the ammonia (he looked like he was dying) moved him into my 55G. He was just floating around there too, but he perked up and started swimming around. He got all of his energy back due to the perfect water parameters. HOWEVER, my angelfish started chasing him. I was in a bad spot - either put him in an un-cycled tank or have him potentially killed by my angelfish. I decided to do a 50% water change on the 20G, then put him back in. Otherwise my angel would have killed him (he killed other fish in that tank in the past - he is extremely aggressive). Now, back in the 20G, he went into his cave and has never came out since. I never saw him come up for air so I was scared he suffocated under there. I picked it up and he swam out, but the second I put it back down he went and his again.
 
 
I am scared he is going to die now. He was never hiding like this before, but earlier he was just floating motionlessly. He was so happy in the 55G so I felt very bad taking him out. I moved him twice today.
 
 
I don't know what to do. I can't put him back in the 5G - it has been completely disassembled. 

 

[BettaBettas]

stop moving him, leave him where he is hes obviously super stress from you moving him around all day. I suggest lay it where it lies

 

[Inchyally]

stop moving him, leave him where he is hes obviously super stress from you moving him around all day. I suggest lay it where it lies

Thank you. That is what I assumed. Do you think he will be coming out tomorrow? I dropped in a pellet to feed him and he is still hiding and didn't eat it. He usually eats fine every night. Even the first two nights in this tank he was fine, it was yesterday when  he started acting lethargic and it got much worse this morning. The 55G solved the problem but the angel would have killed him. I feel so bad for him and if anything goes wrong this is my fault for being irresponsible.

 

[BettaBettas]

just keep him in the tank hes in, don't feed him for 1 day or 2 at max, then feed him a bit he'll eat for sure.

 

[cowgirluntamed]

You need to keep checking ammonia levels and do daily water changes. You are basically doing a fish in cycle which will stress the fish. Only leaving that small filter running for one day won't cycle it. But...good news is you have a lot of water for just one fish! So that will help but lots of water changes are a must until the tank is cycled.

 

[ginaekdal]

Could you not simply have moved the media from the small filter over to the bigger filter? The bioload from a betta is very small. Is the new tank planted? Get some mature filter media in the filter, and stay on top with water changes.