@Christoph S Thanks, I used to make Flash aquariums and it was easy to add bubbles by using a snippet of action code borrowed from the internet. In a gif there is no easy way to do this so they had to be handcrafted but now I have this animation don't be surprised to see bubbless and transparent things appearing everywhere.
@Christoph S .. It is very easy to do so. I have created these animations on an old computer and they display slower on that. If you can open it in an animation program that displays the frames it is just a matter of adjusting the frame speed. I use a really ancient program called Jasc Animation Shop