Future fish

The construct also contains a stretch of DNA from the promoter region of an ocean pout, an eel-like creature that lives in extremely cold environments (the promoter is a switch that controls the expression of a downstream gene). Normally, the eel uses this promoter to keep an antifreeze gene turned on constantly so it does not freeze. The promoter is therefore “constitutive,” meaning it is always active, and coupling it with a growth factor gene in an Atlantic salmon results in the salmon experiencing a continual growth spurt—since the growth factor is continually produced. Studies have shown that the genetically-altered Atlantic salmon’s appetite would make it constantly ravenous, meaning that it would eat everything around in sight.

-- FDA Decision Will Lead To First Ever Genetically-Modified Animal For Consumption