A recent study published in Applied Ichthyology suggests that flash photography of your cichlids may not stress them. The purpose of the study was to determine if flash photography triggered a stress response in the beautiful and popular Ram cichlid (Mikrogeophagus ramirezi), a dwarf species from South America. Cortisol and glucose levels, post exposure to the flash, were measured using whole-body homogenates (e.g., cells). In other words, the fish used in the study were euthanized shortly after the experiment and chopped into pieces where the body cells could be extracted and broken down.
The results of the study showed that the Rams in the experiment had lower cortisol levels than the Rams from the control group. Obviously, the expectation was that cortisol levels would rise from the flash exposure, indicating a potential increased stressor response.
The authors went on to express that the conclusion of the study should not be generally applied to other fish species. In other words, the authors stressed that, if the same study was conducted on other cichlid species, the same results and conclusion might not result. However, the effect of flash on your own cichlids could be similar.
Reference: Knopf K, Buschmann K, Hansel M, Radinger J, Kloas W. “Flash photography does not induce stress in the Ram cichlid Mikrogeophagus ramirezi (Myers & Harry, 1948) in aquaria.” J Appl Ichthyol. 2018;00:1–7. https://doi.org/10.1111/jai.13673