Yellow Tail Congo Tetra's? Anyone Had Them Before?

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They're slowly getting used to me. I only ever feed and watch them, and they're getting more and more receptive me putting food in. Interestingly though the females still seem to be much hungrier than the makes! They'll eat until they've got nice round bellies but the males won't ever eat as much!

I assume it might be something to do with energy required to produce eggs?