Bigger tank first, fish decisions second.
You need a much bigger tank. Everyone else has already covered the choices, though I think most Tetra will be fine with Severum, they don't seem overly interested in live food 99% of the time.
You need a much bigger tank. Everyone else has already covered the choices, though I think most Tetra will be fine with Severum, they don't seem overly interested in live food 99% of the time.