Here's Patchy in his ten gallon unfiltered which gets 100% waterchanges.
His tail is healing nicely from the chunk that was missing from it when I got him. He doesn't have fin rot, the new tissue is coming in marbling blue, weird.
Do you know what tail type/ color betta he is?
In my experience my guys like shallow water so that explains the water level, the plants are pothos which is not an underwater plant but the cuttings do well floating for me and I replace them if they start rotting, be aware that betta can get tangled in their roots if extensive, also got a java fern and "bamboo" half submerged.
He is awesome!
In the last pic he is running away from the camera!