It's easy to tell the difference when they are close up and side by side, but when you are buying it and it's in a tank then it won't be an easy task. Imagine if the tank had white stones in it like mine, then you're in trouble haha.

Is there some kind of limitation to how many different breeds you can have in one tank, or does it just come down to which ones are 'compatible'? I guess the more you add the more you have to mix and match so it becomes more difficult.

I was actually looking to buy one of these, I didn't realize there were such similarities between them! I guess when you're not a pro you just have to trust that you are buying what you think you are. Maybe I'll do some research beforehand next time.