Do 2 schooling species need the same amount of fish in each school?

[GreenGuy]

Can I have 10 Harlequin Rasbora, and only 8 neon tetras, or do I have to get 10 of each?

 

[Dephea]

I have mixed size schools and didn't see an issue Go with what's best for the fish, some require bigger schools, some smaller

 

[Byron]

I agree. Individual fish in a group of a shoaling/schooling species are more interested in how many of their own species are together. Scientifically-controlled studies have determined that too few of the species can cause serious issues for the fish, and not surprisingly keen observation by aquarists confirms this. While too few can cause stress (leading to much worse), I have never known a situation where there were too many of the species [provided the tank's limitations are not exceeded obviously].