ERrr, a guppies and tetras are 2 completely unrelated species of fish. Guppies originate from central America and tetras mostly come from South America. Guppies produce life young (ie livebearer), while tetras produce thousands of eggs scattered all over the aquarium. What we generally call 'peacock fish' which we use as feeder fish are guppies (the wild form). The domesticated form have big nice colourful tails.

Tetras on the other hand are generally shoaling fish which do best in larger numbers in the aqaurium (generally 6 and above is a good number). Some of the more common tetras in M'sia re the Neon Tetra, Serpae tetra and Black skirt tetra.