Best thing to do would be to save up and fork out for a big old wild caught specimen.
From 3-4" (presume you mean inches, not feet!) you could be seeing signs of the mo growing in 12-18 months as it gets closer to 10-12". To get the full blown Tom Selleck you could be waiting years. You need a good size tank, good water and plenty of food to get them growing steadily, and patience if you want that big "old" look. My largest L190 is starting to show them at around 9", but they aren't white like the ones in the pics. Best thing to do would be to save up and fork out for a big old wild caught specimen.
This is your surest and fastest way.
If you haven't had any experience keeping Panaque then a large adult will probably be a bit of a shock.
