it is just God saying He comes out of the water to be on dry land with you & He has the ability to retract His presence to the inside of a small compartment that is connected to you. So He is like a turtle in His present position next to you. He is saying He is your true friend & has been with you for eternity; & has shown you that strange form so that you know He comes from the waters & is able to be on dry land as well.
God is also ancient & yet eternally young at the same time; so will appear one time as an old person & then the next time as a young person. But it is all the same person each time. So God is a youthful eternal friend you have in the spiritual realm & He appears in an older form to let people know that He has been around a lot longer than them & is therefore wiser.
Genesis explains that the universe is under water. It also says that life in all its forms including the birds in the sky will come from the waters.
Other religions teach that God lives under water & creates energy universes such as this one we are in, & sends souls into those energy worlds & then visits them in all different kinds of bodies including half man half fish bodies. This is God's way of saying He comes from the water. It is a water that is all around us just as heaven is all around us on a different frequency or level.
God therefore is saying He has visited you in that form from the waters so that you'd know the position He is in right now, & He is very old; & He has close connections to your true & eternal friend, whom you cannot remember whilst you are in spiritual forgetfulness.