Rummies possibly mating?

[fishboy87]

So I can hopefully give you a clue about this, I have a 29 gallon moderate tech aquarium---

Ammonia -0
Nitrite -0
Nitrate -About 0 or so

Pressurized co2
ZooMed 501 (mainly for flow but has given adequate filtration)

Its been running since about January and I've got rummies around late March. They've all been doing fine and still seem to be but there is one large one (I can't tell if she is pregnant or has overeaten) that keeps swimming to my vallisneria and then starts picking at the floor of the tank near it. Then the school would come over and she would go back and follow them. That started last night after I did a 50% water change with cool water because I don't have any warm filtered water. I do this always though I have found that some breeders use this as a technique to get fish to breed by simulating the cool water as the rainy season when they do breed. There has been another rummy that occasionally comes over and follows her sometimes straying away but usually stays moderately close. To me, this seems like a pair might have formed but I am absolutely no expert as if it is, it would be my very first time breeding egg-laying fish let alone rummies.

Give me your opinion on the matter and thanks for reading