I have the same slime problem but I just assume it’s good bacteria haha
My tank is 10-12 litres so only slightly bigger than yours
I find it hard to think Betta will be happier in a tiny tank.. more space should be better leh.. or maybe he was happy with the Ketapang leave and not the small tank so try putting leave on big tank?
I also don’t turn on my filter all the time , maybe 8 hours a day and off at night so the Betta can “sleep”
Maybe your tank is much bigger than mine bah, I think if i leave my tank's filter/pump on for that long, the betta will be stressed out le. Btw partly my tank is bare with only 4 pcs of moss ball...
Could be happy in small tank cause is new water ?
U got try put the leaf in big tank it doesn't blow bubble ah?
Also the slime thingy could it be the bettas slime coat? (U may want Google this)
no need for filter or airpump for bettas
try putting ketapang in your big tank
I know about the scare about slime coat, because I believe that's what killed my first two betta (male and female) which I reared them together in the the small container which I use to isolate my current betta whenever i do a 100% water change. It looks quite similar to the one below, but it has a divider in the centre.
Back then I did try to place crushed ketapang leaf in a teabag in the 8L tank, somehow he doesn't seems satisfied as compared to isolated to the smaller container with leaf. But that time I was still experimenting which I have plants in the tank (eventually rot and i threw away). Maybe next week when I do a 100% water change I will try to give it a try again.
Btw, is it alright to rear betta permanently in water browned by the ketapang leaf? I am always wondering the water so brown like red tea, the betta actually like or dislike, can survive or not....



