3 tanks.
i love my tanks.
One 3ft holds
6 red eye tetras.
7 white cloud mountain minnows.
7 neons.
2 black skirt tetras
1 albino shark 3/4 inch long
Never had any trouble with the shark as he went in from tiny and doesnt see the other fish as food.
One 4ft juwel 360.
15 cardinal neons
1 breeding pair of spotted cats
7 bronze cory cats
5 black skirt tetras
4 four inch juvenile silver dollars (argentus myletius).
one 3ft
one ranchu goldie
one fancy goldie
2 four inch shubunkins who let you stroke them ,just like pets.
Also kept gouramis varieties but we never had much luck with them.
Gotta love Andys Aquatics
and maybe the answer to your betta problem might be to get a piece of clear thin perspex the height/width of your tank and carefully slide it in and section off an area you could keep him in without him fighting . That way you could still watch him flare .
Ps Burn small holes in it 1st mind so that your still get water movement/oxygen to him