Squids are not spawning

In my world no squids are spawning. I read a few things that said that if there are a bunch of squids in one place it will prevent others from spawning, so i tried /kill @e[type=minecraft:squid] but no entities were found. I've traveled around the world, can't find any squids, I've waited quite a long while in rivers and oceans to see if any would spawn, but none spawn.