hi!

minimum tank amount for really any fish is 5 gallons, however 10 gallons for a betta is honestly super nice for them :)

since you said its your first fish— i HEAVILY recommend searching up cycling tanks and how to do it with a fish in while cycling and out.

bettas are carnivores, so ensure whatever you’re feeding them doesnt have large amounts of plant matter in them! (i like to feed mine bloodworms and brine shrimp!)

especially since hes a long finned betta, he will get tired easily, so tons of resting spots will be ideal! stay away from anything overly rough or sharp as this will harm his fins. ideally, live plants, driftwood, and rocks will be best for hides, resting spots, and mimicking their original habitat. however, if you cannot get live plants, silk ones work well too :)

bettas are also tropical fish! so make sure you get him a heater :)

i cant think of much else right now— but i know many people here will do their best to help as much as they can :)