As mentioned already, good pellets like NLS and Hikari with regular water changes will give you the growth you want. Male Jags will usually grow much larger than females so your male may be smaller now but it will be larger than the female eventually. If you just can't wait to breed them, lay a piece of slate against the females side of the divider where she can lay her eggs and the male can still fertilize them through his side of the divider. You'll need a sturdy divider for this, not that flimsy mesh stuff. Above all else, leave them be. The more you change their routine and rearrange their tank, the longer it may take for them to bond. Be patient.