Well there was a lot of noise in some of them but Elements was able to clean them up fairly good. Almost every photo needed to be cropped to cut out people or shadows/reflections of people. I also used Dehaze on many photos in post processing which helped eliminate some of the cloudiness from the water.
I was seldom against the glass as the place was very crowded. Kids etc running around everywhere. I tried to always shoot directly straight towards the glass. I found anything i took from a side view was simply not worth keeping as the glass and water etc distorted the image adding blurriness etc. I was surprised more glass scratches didnt appear being a fair distance from glass. I would say i averaged about 2-3 feet back from the glass. There were some tanks where i got closer people permitting etc.
Certainly my F1.8 lens really helped get in as much light as possible. But even then when you needed shutter speeds between 1/250 to 1/400 and with the low light you got challenged. So needless to say you had to sacrifice depth of field as you simply couldn't close the lens down enough with the lighting as it was.
Focus wise with my EOS R i tried "Large Zone" or "Expand Auto focus: Around" . If it was just a single couple of fish i shot expand auto around.... when it was a group of fish i went large zone. These seemed to work the best for me.
Also some of the tanks created garbage as the water was so cloudy it was like shooting through a fog.
Lastly as the fish are always moving so i fired dozens of shots of the same fish as they are always changing direction so you never know which photo got the better view etc.
It was good experience for me with constantly changing conditions.