What Type Of Rainbow???? Help

I don’t know what these are and I now own 7 and they are happily swimming in a quarantine tank. I got them at petsmart because no other store within an hours drive carries them. I usually go to strictly aquarium stores and one store said they should get them but it could be months (and I’m inpatient). The sign said Australian but I now know the scientific name actually says it’s an eastern rainbow. The pictures of both fish on the internet look very similar and I don’t have a good eye for determining the difference. The web also gives sizes for the eastern rainbow from 4 to 6 inches. If the eastern doesn’t get much bigger than the Australian I’ll keep them. Help!!!! They will go in my 55 gallon that has:
12 preacox dwarf neon
6 julii cories (I think they might actually be false julli) (will add more
6 pepper cory (will add more)

It las lots of plants, 2 aquaclear 70 filters and 2 sponge filters. It’s 48 inches long, 21 high and 12.5 deep

 

Haven’t seen them in a long time. Here’s a pic of a fully grown one. Yes I also bought them as a Australian rainbow fish. They should be fine with your fish they’re peaceful schoolers. Also they look like small striped bass.

 

Thank you. How big do they get?

 

About 3inches long.

 

Phew!

 

Are they actually Australian rainbows or something else?