Actually that is an amel. Sunglows are just line bred amels. Same with candycanes, they're just line bred amels. If you breed a sunglow and regular amel, you'll get genetically get all amels, some may or may not be sunglows. Likewise, sunglow x sunglow doesn't always give you all sunglows (though it does increase your chances), and two amels can throw sunglows.
As for what makes a sunglow, yes, they have no white on them and are marked by extremely vibrant reds/oranges. Even though some may have no white, they also need to have intense colors to make the cut.
In the case of amel motley/stripe, those almost always have no white on them (other than the belly), but not all are sunglows. In that case you have to rely on the intensity of the color. Here's a comparison of a sunglow stripe and regular amel stripe as yearlings (I need to get new pics as these are several years old)
Oh, and I think yours makes the cut as a sunglow.
Sunglow stripe - note how vibrant he is
Amel Stripe - note how even though she has no white, her colors are much more dull
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