Like the title says, an icon to know that there are fish in there would be nice. Presently it's pretty easy to forget there are fish in there. You can hover over it to see the fish but if you're just swapping characters, you might forget. I lost many expensive fish already lol

for example, behold what it could be, courtesey of ms paint:

Edit: Turns out the starfish isn't a ribbon and does exactly what I was asking. It's just so camouflage. Maybe make it orange or something so it's more clear that it's there and not part of the bowl.

A very small image of the first fish in the tank is shown in the upper left corner of the tank icon, isn't it?

Okay, you're right. As someone has pointed to me on discord, that isn't a "starfish ribbon", that's an actual icon that designates it has fish in it.