Hello I'm still in the process of setting put my 30 gallon tank (L-80cm W-39 cm H-47 cm) it won't be running till next year. I'm still buying substrate as it'll be a planted tank and treatments so it isn't running. I plan on having 6-8 kuhli loaches (it'll be soil with sand ontop for them), a Betta fish and some schooling fish tetras, Danios or barbs. I need help deciding what schooling fish to get and how many as I don't want to over stock the tank and i don't want the Betta getting nipped. Any advice is welcome x
If you're going to keep Kuhlis I would not use a soil substrate. Kuhlis will dig into the substrate to bury themselves and you'll end up with soil floating in the water all of the time.
A Betta isn't compatible with Danios as they need moderately cool conditions, below 24C whereas a Betta will need it to be around 28C.
Most tetras and barbs will nip at a Betta so neither is a good match. You'd be better off looking at some of the smaller species such as Mosquito rasboras, Lambchop rasboras or possibly Ember tetras or maybe Harlequins.
Bear in mind that some Bettas will attack any other fish or be very stressed out by their presence which is why it's often recommended that they are kept alone. It's advisable to have a backup plan ready to go in case he is like that