I got my first sen a few days ago, too. It's really active and loves blood worms. I think I will get another sen or a different species of bichir. They are a bit addictive and act totally different than my cichlids. I'm going to keep them in their own tank. I don't think they would make it with my cichlids.
I'm thinking of having a custom made 36"L x 24"W x 18"H. With enough filtration that should be able to house 5 Sens a Del, and a Retro. That's only around 67g, but with a decent canister and as big a sump as I can manage it seems like it could work.
Bichirs are great. They eat all the time. I just hope they are as active as they are as babies. Probably just like humans. The older we get the lazier we are.
Right now they're all pissed at me because I'm doing a major tank-rescaping, because I had to rip it apart to get the Siamese Algae Eater out. I didn't like the way the biggest of the 3 was looking at him.
I also discovered that they love Wax Worms (Bee Moth Larvae). I'm really spoiling these fish with lots of different live food. I'm going to start making arrangements tomorrow to get them into something a bit roomier.