I have a four foot tank with some guppies male and female, sword tails, neons and cardinal and a red tail shark (just started off). Can i add a male betta or not.
No Im afraid male and female bettas cannot live together, they will fight, you could have a group of females though, 5 females should be ok to spread aggression but this is your max for a 3 foot with no other fish
There is a reason why they are called Siamese fighting fish they will bully and rip each other up if kept in the same tank permanently, ultimately leaving the weaker one to die eventually males and females should only be introduced when breeding.
Best tankmates, without knowing what the bettas personality will be like...
Maybe cories.
Really just depends on the betta. Sometimes they'll be ok with tankmates.. other times, they won't tolerate anything with them.
Best just to get a betta it's own little tank to call home.