The number to put in with your betta will depend if you go with pygmy cories or with standard size cories. Also depends how often you maintain your tank. Concern is overload, right?
You could probably get away with 4-5 pygmies, or 1-2 regular cories with your betta. Different bettas will react differently too - so be prepared for potentially having to make a change.
I just thought of another consideration - bettas, as a rule, like still water. Cories tend to like current. So there's a bit of a difference there. When my betta and cory were sharing a tank, the cory was fine with the low water flow - but I had to try and find a balance. Either that or make sure there is a portion of the water surface that is calm so your betta can make his bubble nests - I've even seen people use a styrofoam cup, or one of the plastic cups bettas come in, as a protected area (flip it upside down, and there you go - betta nest dome)
You could probably get away with 4-5 pygmies, or 1-2 regular cories with your betta. Different bettas will react differently too - so be prepared for potentially having to make a change.
I just thought of another consideration - bettas, as a rule, like still water. Cories tend to like current. So there's a bit of a difference there. When my betta and cory were sharing a tank, the cory was fine with the low water flow - but I had to try and find a balance. Either that or make sure there is a portion of the water surface that is calm so your betta can make his bubble nests - I've even seen people use a styrofoam cup, or one of the plastic cups bettas come in, as a protected area (flip it upside down, and there you go - betta nest dome)
