In my grow out tank I have a female GT and male JD, they've been together for 6 months and are now about 4". Lately she's been shimmering and shaking in front of him, she's dug a hole and the two of them do not allow any fish near the corner of the tank, there is a male GT in the tank but she's always with the JD. They are definitely acting like a pair. Is this even possible?