I have a 10.5 gallon tank. THe goldfish started chasing my tetras initially (tetras were introduced to the goldfish after a few days) but after a week they are peaceful and ignore each other completely. I dont know the breed of my tetras but size and shape are similar to neon tetras except not as colourful. Mine have a red line above their eyes.
This forum has a wealth of information and it is very helpful especially for beginners like myself.