What they said:
feeding: once every other day with betta flakes.
water changes: 20% - 30% weekly
Tank size: 6 litres minimum so about 1.5 US gallons
Temp: room temp
I am battling fin rot at the moment as he was in a 1 litre tub which was unfiltered and looked quite dirty. I got did get him at a huge reduction for it, I paid £1 for him instead of £9.99 which is about $15 usd, so I paid $1.50 instead.
How I am keeping him:
feeding: once daily, 4 days of the week 5 betta flakes once daily, 2 days of the week 3 defrosted blood worms.
water changes: 30% weekly
tank size: 33 litres (8 us gallons) and filtered which doesn't cause a big current, With bio media from a cycled established tank.
temp: 26c now 28c as heater doesn't do 27c