1) I heard a [store]employee tell a customer that they should put in their new 10 gal
tank, as first fish, 1 oscar, 2 guppies, some platies and some neon tetras. I laughed. ( Thankfully, they didn't listen and just got some guppies.)
2) Bettas don't need clean water- pet shop employee
3) Bettas need 10 gal
. aquariums to keep multiple males in them- too many people on internet forums.
4) Breeding fish like other fish in their tanks- pet stores and forum posts.
5) ANY kind of algae you can grow is good algae- Chain store employee