There were several parties of well-to-do looking school kids when we visited but the aquarium is large enough to find a quiet (ish) corner in.
It is everything you’d expect from a modern aquarium, a wide variety of sea life contained in distinct areas, low lighting for deep sea creatures, open tanks for “pettable” marine life and so forth. And of course be prepared for the strategically sited gift shop and the end of your route!
To get there the easiest way is to take a skytrain to Siam station and follow the signs.
Please forgive the rather dubious quality of the photos, I’m no photography expert and taking clear pictures in dark light is not my forte!