I have one Synodontis which I call Chocolate. He is the farthest thing from aggressive! When we first got him, he took an instant liking to his Pleco tankmate. He would constantly lay on Pleco's back. Pleco didn't mind, which was suprising. He doesn't do it anymore since he is so much bigger now. He likes to eat live feeder fish and sinker wafers. He gets along with everyone in the tank.
The feather, fin in my personal opinion, is the most beautiful of the Synodontis species. They have been a joy to watch grow (and they do so fast) and make beautiful centre pieces to a community tank. I have two and they only bother each other, no one else.
This Featherfin has to be my favorite fish. I have several tanks from 8 L to 340 L. He is currently in a 200 L with tiger barbs. For a catfish, I'm amazed that I see him often in the daytime. I have had no problems with aggression towards other fish. I have a large piece of driftwood in the tank that is covered with Java moss, he loves to lay in a notch towards the bottom. I have had no fry in this tank, so I guess he must be eating the eggs, but then barbs are known for this also. This is a super fish, very beautiful for a catfish.
I have 2 featherfin squeakers in a 280 L New World Cichlid tank, and they get along great. The Cory catfish I had in there, however, did not. I had 6 Cories in there, but the cichlids poked their eyes out. Just goes to show that the Featherfin's more aggressive nature makes them more adaptable to an aggressive tank in this instance.
I am keeping 1 Jack Dempsey (12 cm) and 1 Green Severum (~12 cm) cichlids in ~230 liter tank in company of Synodontis eupterus (~14 cm). The cichlids are beautiful, but I would say, despite his rather drab coloration (deep brown with almost black polka dots) the feather fin is the most impressive fish in the tank. He is not shy. He is cruising the tank constantly with his amazing fin upright and keeps his eye on me when I am going to come to feed them. He absolutely loves live blood worms and fights for them with the Jack Dempsey. He also likes to snack on spirulina wafers. He's a very quick grower and for 3 months that I had him he grew at least 3 cm. In short - a remarkable fish with great personality.
I have had a featherfin for about 3 months, he has grown from about 6 cm to about 12 cm and has at least grown in bulk 4 or 5 times. He is with a gibbiceps pleco, 5 assorted corys and 25 or so smaller, peaceful fish in a 100 L, well-planted tank with a lot of rocks and rootwood. I feed small amounts 3-4 times daily, usually freeze-dried bloodworms, flake food and sinking cichlid pellets (he eats mostly the latter). He is very active, especially at feeding times (a greedy eater), and he bumps the corys around like bowling pins to gather up the food. The corys (aeneus, julii, and paleatus) don't seem to care and are right back at it. My featherfin has been nothing but a delight for me.