Hi, a male Betta in a 5 gallon tank?.......lucky boy! I know it can be tempting to put other fish in there as it seems a large tank for just one fish
Each Betta has it's own personality which seems to be the main attraction. They are the nearest thing to having underwater dog if you follow my meaning. This means that some will (and do) live quite well in a community set up providing certain guidlines are followed and some, as previous poster mentioned will not even tolerate a snail!
Please do not think that a female betta is the answer

The breeding conditions are not for the novice and should be completely researched before attempting, ok?
In a Betta tank such as yours make sure you have plenty of 'playthings' for him to relieve boredom which could lead to self-harming (tail biting) Remember, Betta's are like dogs, curious, mischievious, playfull and full of character. So, plenty of plants, caves/pipes or nooks and crannies to investigate. Nothing sharp that could catch his fins.
Now then, back to tank mates. In mine you will see I have eight Pigmy Cory. This has been fine for some months now. At first he would chase them about but ony for a few seconds at a time. Now he ignors them unless a few are in the cave together then he loves to chase them out, scattering them in all directions (I'm sure he's laughing at the time

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This works for mine and his set up, yours may be different but you wont know until you try. Just watch the behaviour and be prepared to take action rather than stress the fish.