Additional evidence of chemical cues in cichlids

Chemical structure of uric acid. Image from

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.

Can fewer water changes be better?

Pterophyllum scalare. Photo from Arizona Aquatic Gardens.

Frequent water changes are widely hailed as a key variable in the well being of aquarium fish, especially cichlids. However, for at least one species of angelfish, fewer water changes may actually be beneficial, especially if your angelfish population is somewhat dense.

According to an article published in the January 2018 issue of Applied Animal Behavior Science, frequent or large water changes in aquariums housing Pterophyllum scalare may actually increase con-specific aggression in this species. The authors posit that water changes modify cortisol and other chemical levels that these angelfish use to establish social status. Frequent and/or large water changes dilute these chemicals, which effectively disturbs the baselines that set the statuses thus requiring that the angelfish re-establish them.

Less water renewal reduces effects on social aggression of the cichlid Pterophyllum scalare. Gauy, Ana Carolina dos Santos et al. Applied Animal Behaviour Science (2018). Volume 198, pp. 121 – 126.