If you need money for seeds,houses,food etc you can sell it but if you want a new picket over the money then you can go ahead and trade it if it is alloud.

there's both an upside to keeping the egg and hatching it (double the hoard, and potentially double the legendary eggs found during hoards if it hatches out to be another aqua! potions will be needed though and with potions comes ingredients which cost money... )

but selling the eggs is also beneficial, like someone has noted, because you will be able to get some PC to afford ingredients, food, etc.

personally, i would try selling the egg and see how much it fares!