i have a visionarium for the snake im gonna be getting. aquariums are really designed for fish, not snakes. the visionarium has a little bit of screen on its top but that can be easily covered with aluminum foil. it also has front sliding doors and theres also a special lock that fits on those sliding doors. i have a lock on mine. also, with both the visionarium and the fish tank you'd have to cover up 3 sides with something, could be a background or something else. i have a terrarium background covering mine.
good luck with whichever you choose.