molly, platy, swordtail, guppy, endler.
all of these are livebearing fish, and are the best to start with on your aquatic breeding journey.
you said you have six tanks, so keep two empty for the fry when they are born... or three
livebearers are usually already pregnant when you get them from the store anyways (all of mine were)
my platy averages one birth every 4 weeks, and my biggest molly averages one every 5.5
i usually get about 25-35 fry per birth (if i catch it)
you need hiding places if you dont plan on seperating the pregnant females
(i do the hiding places technique because i dont like to stress out mommy)
molly fry will swim close to the top because they like the light, so floating plants are recommended for fry cover (in my experiences, anyways)
and platy young will take cover in the gravel/bottom decorations
best of luck, and happy holidays!
