I have heard some people say that Parachanna obscura are extremely mean/aggressive and cannot be kept in community tanks? They usually are high temperment fish and territorial, the majority of the time, but I don't think it is impossible to keep them in a community tank. I beleive it can very well work, as long as there is enough tank space, hiding places, and be sure size range of all fishes are relatively the same or compatible.
A buddy of mine had a 14" obscura in his community tank. Got along fine with tankmates, showed no aggression at all. Tankmates housed were a larger size endli bichir, datnoid, spotted gar, arowana, juruense cat, and a couple rays (from teacup to 12" size). Tankmates that you are actually planning to keep, he also was keeping.

The obscura speciman he kept was fairly mellow and passive... so laid back that he was even able to pet, hold in his hands, and pickup out of the water... was a total pussy cat!
Anyhow, most important to keep in mind and remember is to get a 'feel' of all your fish (personality, behavior traits/patterns, etc.) and find a
'balance point' amongst them all. Be interactive and take time to watch and observe... day & nights). You may just come to find out that perhaps one (or more?) of the tankmates that you intend to keep, you may just not be able to be keep afterall??... short term or long term? You may also need to step up & upgrade to a larger tank, other than your current 100g tank now? Anyways, good luck to you and enjoy!
