very nice fish. B. imbellis are a little bit shy. Your Tank should already have from 50 l.
Betta kuehnei,Channa bleheri,Channa limbata/gachua TH03/02,Channa sp.'Inle ',Channa pulchra,Parachanna obscura,Trichopodus trichopterus,Trichogaster lalia,Macropodus spechti "Dong Hoi"
You need more Plants and dark backside in your tank.
Now it will be 3 weeks since i bought them,i have one 54 L tank but it is to high and i have another tank 60Lx25Wx18H i was thinking to move them in this smaler tank,i would put black soil on the ground but i just started soaking the soil and it takes 4-5 weeks until it will be reeady for use.
i could just change blue back with black one so they feel more secure.
Hello and welcome here,
a typical 54-l-tank (60 cm x 30 cm x 30 cm) is not to high for B. imbellis. Smaller tanks make them shy. And you should cover half to 2/3 of the surface with floating and / or swimming plants.
Much pleasure with your nice fish,
As Claus mentioned, your tank is not to high. Most of us don't fill their tanks to the top. some 20 - 25 cm. is enough.
If you fill a planted 54-l-tank completely the water will have a heigth of 20 to 25 cm only. That is no problem für Betta.
Klaus (with "K")