How many six line in a tank?

[pontiac2002gtp]

Can you put more than one sixline in a tank? How can you tell if they are male or female?

 

[tanglovers]

I have two in my 220. I added them at the same time and added a larger and smaller specimen together. There were and still do this day (over a year later) no aggression issues between the two of them and most of the tim they can be found within a foot or so of each other.

I have not noticed any spawning/mating behaviors and they do not appear any different at all in appearence.