It's not about the algae, it's about the critters that hide beyond the cracks & crevices of the rock formations found in the crater lakes. The search for those critters is what creates the hypertrophied lips, in certain African cichlids, and speculated the same for crater lake cichlids.
SPECIES‐SPECIFIC DIFFERENCES IN ADAPTIVE PHENOTYPIC PLASTICITY IN AN ECOLOGICALLY RELEVANT TROPHIC TRAIT: HYPERTROPHIC LIPS IN MIDAS CICHLID FISHES - Machado‐Schiaffino - 2014 - Evolution - Wiley Online Library
But no doubt that the increased aggression is about territorial disputes. I once watched a small tropheus fry defend a sponge filter. lol Anything that adds structure can be considered territory, for feeding, hiding, spawning, etc. With aggressive species, as unpleasant as it can be aesthetics wise, with large groups of fish a bare tank will help keep the community calm.
SPECIES‐SPECIFIC DIFFERENCES IN ADAPTIVE PHENOTYPIC PLASTICITY IN AN ECOLOGICALLY RELEVANT TROPHIC TRAIT: HYPERTROPHIC LIPS IN MIDAS CICHLID FISHES - Machado‐Schiaffino - 2014 - Evolution - Wiley Online Library
But no doubt that the increased aggression is about territorial disputes. I once watched a small tropheus fry defend a sponge filter. lol Anything that adds structure can be considered territory, for feeding, hiding, spawning, etc. With aggressive species, as unpleasant as it can be aesthetics wise, with large groups of fish a bare tank will help keep the community calm.
