The tank bettas actually thrive in
The tiny cup a betta is sold in is transport packaging, not a home. A first betta tank should be at least 5 gallons, and 10 gallons is genuinely easier for a beginner because a bigger volume of water drifts out of condition more slowly. Bettas are tropical fish from warm, still, heavily planted shallows, so the whole setup follows from that: warm water, almost no current, plants to rest in, and covered surface. Get the tank cycled and running before the fish comes home, and put it somewhere out of direct sun and away from doors that bang, since bettas startle and stress easily.
Heat and gentle filtration
A small adjustable heater is not optional equipment for a betta - it is the difference between an active, colourful fish and a sluggish one sitting on the gravel. Hold the water at 78 to 80 degrees and check it with a simple thermometer rather than trusting the heater dial. Filtration should be the gentlest you can manage: a sponge filter, or a small hang-on filter with its outflow baffled by a sponge or bottle baffle. A betta's long fins act like sails, and a fish fighting current all day exhausts itself and may bite its own tail. Surface access must stay clear, though, because bettas breathe air at the surface with their labyrinth organ.
Planting and decor that won't shred fins
Run a fingernail or a pair of old tights over any decor before it goes in: if it would snag tights, it will tear betta fins. Choose silk or live plants - anubias, java fern and soft stem plants all suit - and include broad leaves near the surface, because bettas sleep resting on leaves close to the air they breathe. One smooth cave or coconut hide gives him somewhere to retreat, and the rest of the layout can stay simple. A tight-fitting lid is essential: bettas are determined jumpers and will find a feeding gap in the cover within weeks. Leave a small air gap above the water so the air he breathes stays warm and humid.
One male, on his own
Male bettas were bred for generations to fight, and two males in one tank will battle to the death, so a first tank holds exactly one. Females can sometimes live in groups, but that is an advanced project with real failure rates, not a starter setup. Even tankmates need care: in a 10 gallon, a few snails or a small group of peaceful bottom fish may work, but many bettas harass anything colourful or slow, and shrimp are often hunted. For a first tank, a lone male with a snail or two is the reliable recipe, and a betta kept singly is not lonely - he is territorial, and the tank is his.
Feeding and the first weeks
Feed small meals of betta pellets once or twice a day - his stomach is roughly the size of his eye, and uneaten food fouls a small tank fast. Frozen bloodworm or daphnia once or twice a week adds variety, and one lighter feeding day a week does no harm. In the first fortnight, watch for the good signs: exploring the whole tank, flaring at his reflection occasionally, building a bubble nest at the surface. Flat behaviour, clamped fins or refusing food for more than a couple of days in a new setup usually traces back to cold water or an uncycled tank, so test the water before assuming illness. First tanks generate a stream of small worries each week - is that fin edge normal, why does he rest so often, should the water look that way. For each of those worries, put a follow-up question to KinsLe's Kimmy; she answers using the KinsLe Answers library.