How fast do Jack Demspey's grow.

This isn't a completely exact answer. Like all animals, the growth depends on things like: nutrition, environment and genes. With a healthy and ample amount of food through it's first year of life, it will grow quite a bit. The environment is just as key as if the fish is too small of a tank, it's growth can be stunted and do irreversable damage to the fish. And of course, it's genes may tell it to grow fast while, another fish may have genes that tell it to grow a little slower to or maybe not reach it's maximum size.

So, now that I've bored you with that long response, they will grow to a full size of 7 to 8" in about 2.5 to 3 years (usually) and will be to atleast 5 to 6" in it's first year. So, as you can tell, they do most of their growing in the first year or so. Hence, why everyone always says to make sure you have a big enough tank for the fish when it's full grown because they grow so quickly Good luck with any adventures with this great fish

under ideal conditions they should be full size in the first year.