I don’t have an aquarium, but that’s pretty cool! I see that they even have an add-on that includes the close-focus lens without the magnetic mounting part, which makes me wonder how the focus/view compares with the Bird Feeder’s Lens Bracket that users have been requesting for some time (and which may be available soon). I also wonder how useful it would be for capturing video of snail feeding behaviors.
Welcome to the Forum, @nicholb! 
Thanks for sharing!