First, the new environments and now fish renaming! Yes, you read it right, you can now give names to your fishes.
To rename your fish, just click on it and choose Rename. There is also another option which is the Nudge, when you choose it, your fish will swim away as if you tapped the aquarium glass.
Type the desired name and press rename
Your fish now have its name!
And when you try to sell your named fish, this message will appear,
This is indeed very useful especially if you have your favorite named fish, and when you accidentally clicked the net on it, you still have the option to not sell it.
There is also a new menu that appears whenever you buy a fish.
Those fish illustrations are cute!