We humans are pretty famous for our workings with plants. We purposefully grow them in farms and gardens for food, decoration, raw material, and so on. The plants depend on us, and we depend on the plants. Until now, we assumed this to be very rare, done by only us and leaf-cutter ants.
Discovery news is reporting that one species of fish, the Damselfish, grows intricate gardens of algae for personal consumption. It cultivates the algae, consumes algae that grows beyond a certain height, the way that a human would mow a lawn, and weeds out unwanted species, discarding them outside the garden. More unusually, different fish show different patterns of growth, with some tolerating several species of algae, but others demanding a monoculture of their favorite. Almost as if they had individual personalities with strong or weak preferences. The fish also tended to compete for the best sites, but could be persuaded to quit a claim if it were too hotly disputed.
A biology study on the fish's digestive system showed that the algae that they threw away as weeds tended to be higher in fiber, which apparently the fish had trouble digesting. The preferred algae species tended to be very digestable by the fish.