I've had my sengalus since 3", now 7.5", recently had a black line appear near it's head. Not sure where it came from either but seems like mine's not the only one
Strange that it shows up on one of the dorsal spines as well. Doubt its worth worrying over. I would guess genetics are suspect. Is it whole scales that are black, or does it appear to be above the scales? Just curious.
There's all sorts of markings that develop on bichirs as they age.... perfectly normal.... particularly black spots on wild caughts.... i have a sp. Koliba that was about 12"s when I got it with regular markings.... a year later....it started developing MANY black spots of all sizes.... most notable on lighter based specimens......