Why does your Betta stay at the bottom of his tank nose down?

He's probably sick. Bettas get very stressed by being kept in a bowl. Bettas, like most other fish, like to swim around. A single betta needs a 6-10 gallon tank with a heater and filter for optimum health. Plants and caves make it more interesting for him and a couple of rasboras might work, depending on his aggressive tendencies. They can't be kept with other bettas, but do appreciate tank mates if they have room. The red ones tend to be more aggressive. If he is aggressive, he will not do well with other fish unless he's in at least a 30 gallon tank. People tend to think they don't live long, but if they have enough room, clean water, and consistent temperature, they will be much less stressed and can live for a lot longer than expected.