Many methods and treatments in aquaristics are often perceived as universal solutions. However, every intervention has two sides: potential benefit and possible harm. The “Avers / Revers” section examines common approaches to fish treatment, prevention, and husbandry from two opposing perspectives. Both the positive effects and the possible risks associated with the use of medications, dyes, antibiotics, and other interventions are considered. The purpose of these materials is to demonstrate that the effectiveness of a method always depends on context, the physiological condition of the organism, and the characteristics of the system. A thoughtful approach requires evaluating not only the potential benefits, but also the possible consequences of applying a treatment.