penguin tetras and red eye tetras

Getting my 30 gal. quarantine tank ready to grow up my schoolers to eventually be in my 90 gal. altlum tank...Both the penguin and the red eye attain a length of 3" far as I can tell, that's about a long as S.American tetras grow...does anybody see a down side to my choice...I'm not experienced with altums(yet), but I doubt that they'l eat a 3" fish.Ken