Number of LEDs i can connect

Hello. I would like to ask: can I connect a lot of LEDs in paralell, in 1 PIN ?
I know that paralell connection distributes the same equal voltage in each paralell (5V),but:
paralell also reduces current the more paralells you add.
So in paralell the voltage is the same no matter what number of paralells (5V), but I would like to know what happens with current. The dc current output of 1 PIN is 20mA(or 40mA maximum), but will this same current flow in each paralell equaly, or will it be keep decreasing until it reaches a low level that none of the LEDs can Turn ON?

The current a LED takes is set by the value of the current limiting resistor in series with the LED (you must have one). If you calculate the resistor for e.g. 5mA, then you can have up to four of those "LED+resistor" strings connected to one pin. Yes, each LED must have it's own CL resistor.

What is your real problem. Why do you want to do that.
Tell us more. There might be other solutions.