Male or female jack dempsey

[Swalker]

Ok this Is what I've been observing with my male and female JD's. When the lights are on the chase is on and she goes too one side and he goes to another side then he'll go find her and she'll kind of nip at him but not really then she'll make a sudden movement then he's after her. When the lights are off they're fine side by side not a problem anybody else observe or experience this what did you do? Is it normal