Just after the larval stage, the pattern development stage is very very brief, where pattern turns from a network of horizontal lines, to the complexly detailed patterns that form a basic pattern of spots and stripes.
To sum it up, what you see is what you get when it comes to just about all bichirs, except maybe ornate slightly.
A delhezi with spots, or half stripes, etc.. (usually captive bred on a farm) will never develop the stripes of wild specimens.