I know the point of predators is to hunt other fish but I've noticed that it is really difficult (potentially impossible at some point) to introduce predators into an ecosystem later on when the herbivores and filterfeeders have already learned to swim kind of well.
Having some sort of "pseudo-plant" (maybe something like ground covered with worms or small crabs) would help a lot with getting predators to a point where they can actually do more than fumble around while starving to death.
Having some sort of "pseudo-plant" (maybe something like ground covered with worms or small crabs) would help a lot with getting predators to a point where they can actually do more than fumble around while starving to death.