We are not allowing screen time for at least one year. My son is now five months old and the most screen he’s seen is the occasional FaceTime with his grandmother in another state, and we usually keep the phone turned around and use the back camera.
He's gotten old enough to look around a lot and he loves watching our goldfish tank. It’s on the TV stand below the TV. We play music but keep the screen off.
My immediate reaction is that it’s not screen time. It’s real life, the lights are constant and the fish move slowly and continuously (like it doesn’t jump from one image to another like TV images).
We have moved his little seat over to the tank and he absolutely loves playing with his toys and watching the fish. Now he is always turning his head towards the tank and trying to see the fish. This is what concerns me. He seems to be getting obsessed.
So, what is your opinion? Not on limiting screen time, just on whether or not the tank is psychologically and developmentally “screen time.”

Re: Is watching a fish tank the same as watching TV?
However, if you are using it like screen time (plop baby in front of it and let it entertain him), you may experience some of the same negative effects and may want to vary your routine a bit. A big reason why screen time is bad for babies, in addition to the flashing lights and quick movements that you note, is that we tend to talk to our children less and give them less opportunities for developmentally appropriate activities while they're watching a screen. Putting him in a baby seat, playing music, and having him watch fish would do the same thing. Make sure you're getting plenty of tummy time, very limited or even no time in "containers" (bouncers, jumpers, seats, positioners, exersaucers, walkers, etc.), and lots of time with you talking with and interacting with your baby and playing with real objects.
https://web.archive.org/web/20220126230733/www.cariebertseminars.com/blog/top-10-criteria-for-buying-high-quality-toys-for-toddlers-preschoolers
And
https://www.naeyc.org/resources/topics/play/toys