My Male FireMouth is roughly 5", and I have had him for about 4 years now. The Female FireMouth is roughly 3"-4" and have had her just as long, they just spawned for the 3rd time in a month and a half, I got their water parameters just right in their 55g tank without using spawning aids.
As for having my hands full with my EBJD's, nah my baby ebjd's seem very healthy and are very active. They love the HBH Super Soft Pellets over anything else I feed them. My 6" EBJD is very healthy and active also. The only time any of my EBJD's aren't active is when I turn the tank lights off at night, they seem to calm down quite a bit and relax, but once I turn the lights in the tanks on, man they get so active right away.