There are a few topics on this type of thing already. You can find 1 topic on it
here.
A few tips:
1. Make sure your grandstands are only 1 tile away from the show tank.
2. Make sure your shows are not set to 'never'
3. Make sure you have tricks in your shows. Click the exhibit platform and you can customize the show. Try to avoid doing the same trick twice.
4. Make sure you have a marine specialist assigned to the exhibit.
5. Make sure your tank is deep enough.
6. Make sure your animals can get into the show tank-look to see if the pass through portal is there between the normal tank and the show tank.
7. Make sure nothing is blocking the grandstands or the way to the grandstands.
:closed