i have cardinal tetras,
neon tetra, head and tail light tetras, penguin tetras and male and female guppies and they never bothered each other. the tetras occasionally have a tif between themselves, but the guppies never got involved....they're too busy scavenging for food!! just make sure the tetras are in schools of at least 5. fewer than that and they can feel threatened and get nippy as a defence. saying that, mine have reduced to smaller schools and aren't getting nippy. just something to bear in mind
