Because most cichlids exhibit aggression during breeding and territorial defense, a common solution to reduce such aggression in closed systems is the introduction of sightline barriers. This can come in the form of plants, rocks, wood, decorations, or even sand piles. The basic principle is that blocking the regular view of one cichlid from another will reduce aggression between the two. However, relying solely on sightline reduction to mitigate aggression in cichlids is often futile. Why?
Back in October of 2018, I posted about how water changes can upset hierarchical dynamics of cichlids. That post was about a recent scholarly journal article focusing on angelfish. The premise was that the removal of tank water and the introduction of fresh water during a water change dilutes the chemicals that angelfish expel and depend on for social status reconciliation.
A couple of days ago, while looking for some additional information on chemical cues, I found a very interesting article published in 2015 titled “Chemical communication in cichlids: a mini-review“. This article covers chemical communication in cichlids within multiple contexts (e.g., reproduction, social hierarchies, recognition). I would encourage you to read it when you get an opportunity.