>I don't know why you've considered njisseni nasty. I've got several >wild caught pairs of these fish in with BIVs, E. sexfasciatus, cardinal >tetras, otocinclus, and D. filementosus. I've only seen aggression directed at >other njisseni and never anything vicious at the other fish. I consider them nasty because my first big wild batch -- about 16 in a 2 x 4 foot tank (~80 gallons with lots of floor space) killed about 20 cardinal tetras before deciding to kill each other. Eventually I had one nijsseni in the tank, and about six cardinals.