Lol I obviously didn't know if I told them he was a delta and no I wouldn't do that on purpose. He should have more white/transulcent around his edges for him to actually be a butterfly right?
Oh okay, I never know just because there are people who would do that is all! I know our stores around here are having issues with people switching lids and all, but all is well.
To be classified as a Butterfly it just needs to have a band evenly all around all the fins. It doesn't matter of the color but the band should be clean, but sometimes it can become messy and so they aren't so clean like your boy but he's still sort of a butterfly. Here are some examples of different Butterfly patterning.
Traditional Blue Butterfly
This is a Mustard Gas but they are basically a Bicolor Butterfly.
Another Blue Butterfly but with black banding
A black Copper Butterfly
Salamanders are also a variation of the Butterfly. Very similar to Mustard Gas although the original creator of the MG didn't want this lady to call her fish MG since he wanted to keep it clean and so she called her stock Salamander which need butterfly banding of any color but usually white and then darker color fading in to the body where it is generally fairly solid.