Fry staying on top of tank

[kwi]

I’ve never considered that before. Guppies mouths up, tetra mouths middle, cory mouths down.

*mind blown* (genuinely)

Yup evolution is good like that, it's like eye positions in predator/prey species too. Predators usually have eyes on the front of their heads so they can use binocular vision more effectively where prey usually have them on the sides to increase their periphial vision.