There are some real bichir experts here, like beblondie, but I have (briefly) kept this species and found it to be rather mild-mannered towards different species such as cichlids or catfish. It is a fairly large species though, getting to about 30 cm or so, which puts a 30 gallon tank probably at the low end of what suits this fish.
If you were choosing tankmates, I'd tend to look at things like Synodontis spp. and plecs of various kinds. Climbing perch work well with bichirs provided you choose appropriate species. I kept Ct. acutirostre and Ct. congicum with Polypterus palmas for many years and found they got along very nicely.
P. senegalus is generally considered an excellent bichir for the beginner. It is hardy, eats anything, and becomes very tame. My only caution is that it -- like all bichirs -- is an excellent escape artist. Keep the tank covered, and never give it the opportunity to jump or wriggle out.
Cheers,
Neale