The main inhabitants of my 30 are 6 bosemanii rainbows. 1 is older than the other 5, and is quite large. There is also a large albino bristle pleco, and several cories.
A few months back my sister asked me if I would take one of their old fish, as her daughter was taking down her tank. They brought over a bullseye catfish maybe 4" long, and said he spent most of his time motionless. I put him in with my rainbows. He apparently likes my food, as he's gotta be 6" long and quite thick. I read they are nocturnal, and he spends most of his time hanging under some wood with the bristle, or motionless, deep in the hygro. But late in the evening, several times he will come out from under the wood and follow the biggest bosemanii around, back and forth. I swear, it looks like he is saying "Can we play?" Cracks me up, every time.
Tho he has a huge mouth and an appetite to match, he has never shown any aggression towards any ofthe smaller fish, which would easily fit in his maw.
(Big dog fan here. Just learned last week that Daisy - our 10.5 yr old golden, has lymphoma, and we'll be putting her down in a matter of weeks/months.)