Well, this is in regard to bottom dwellers such as catfish in general, but I'm more likely to keep a pleco (or several plecos) in the future. This probably isn't good practice, but I do roughly an 80% water change every week (over stocked tanks spike to 80 nitrate very quickly, but I'm slowly transferring and giving away my fish) and I noticed that my pleco, while other fish are freaking out, is perfectly okay. In fact, when the water is low, it likes to swim around the decorations, lay in the bubbles, attack floating anacharis that is now closer to the floor, etc. I do my water changes near evening so that's why it's probably more active. But I'm not really sure if it actually likes more shallow water. I absolutely adore plecos and plan on getting a bristlenose once this common one finds a happier home in a pond. It would be nice if I could keep water more shallow so I can use smaller driftwood or have less of a hassle pinning down spinach. Plus, I might be able to give it plenty of space to swim around at night while only having to change roughly 25% of 100 gallons each week if I build my own fish tank.