I have never kept a solo wet pet before, and I feel like some reasons as to why some of us aquaria hobbyist, that don't keep solo wet pets, but have community tanks is for that very reason, diversity. Either it being small community fish tank, or predatory community fish tank, there is just more features about a fish that not one fish will all have, which one of several reasons why I have multiple community tanks. For instance, I have bought 3 different kinds of mahseer from Fugupuff, a Neolissochilus stracheyi, a Tor sinensis, and a Tor putitora. Each one with a fascinating feature to them and how nature has progressed differently with each one, for instance, progression listed left to right, has a shorter head, then it gets a little longer, and once it hits the himalayan it gets quite narrow. This also gives a different behavior for each one, stracheyi for instance just swims around till I give them food, while sinensis from time to time will do a little gravel sand sifting, while the putitora will always be taking advantage of its evolutionary snout and be ramming its snout straight into the sand/gravel to sift on a daily, as which the other two mahseers have trouble doing or dont even do at all. Plus its interesting to watch how they interact, I keep them with some hampalas, two other mahseers, and some other cyprinidae and siluriformes, also experimenting with social behaviors with more aggressive fish like black wolffish, but in that tank only the sinensis and the putitora will fight once every two weeks or so and bash their bodies against each other, very cool to watch. You can see my love for a community tank, get so much info just by watching multiply fish rather than one in my opinion.It also depends on the fish as well, as most people have posted in this thread, a majority of fish kept solo are not necessarily aggressive but instead VERY territorial, and I say this because I feel like aggressive and territorial are two different things, since we hobbyist can only try to mimic an environment but never a true containment of water, as to why flowerhorns would sometimes take over an entire tank to itself, since it can basically feel the whole container it lives in, otherwise in the wild, I doubt you will ever find a flowerhorn and a jaguar cichlid duking it out to the death. And for aggressive fishes, would lean more to fishes that aren't territorial, like the African tiger fishes, they are more migratory, very unpredictable, passive one day, the next, see a chunk of your prochilodus missing from the tiger. All in all though, these are just some small details that I really like about community tanks and as to why I dont keep solo wet pets, more diversity and more things to see in my opinion.