Tetra’s are among the most common and popular tropical fish, due to their small size but very strong colouration. They are easy to keep and can be housed with almost any other non-agressive species. Tetra's small size and nature often means they will ‘school’ together in the aquarium, making a very nice looking ‘group’ in which they will swim around the tank in.
There are countless types which are mainly peaceful, but a few, like the congo tetra, are more aggressive and you should talk to your Local Fish Store about compatibility before you make the final decision of buying, maybe start off with the more popular neon tetra.
When you purchase tetra's, make sure you get at least 3 or 4 of each type to make the fish feel more secure. If you throw in one of each type, not only will the tank look unorderly but the fish will feel more stressed and unwelcome.
Be aware that tera’s will grow a little and size up but they will most probably not reproduce within the aquarium, it doesn’t matter how long you keep them for. Also be aware that the beautiful Congo tetra will grow fairly large and in a small aquarium will be more aggressive to smaller fish.