The problem of food waste at the post-consumption phase, as well as its rational management, is one of the central matters of the transition process undertaken by the European Union, and it is one of the priorities in the Action Plan for a Circular Economy. In particular, the waste of fish products occurs throughout its supply chain. A wide literature is provided in analyzing waste on the first part of the fishing supply chain while high importance is also given to its consumption phase, especially regarding dynamics, causes and social behaviors. The paper aims at investigating mechanisms and causes of wastage that occurs in the last part of the supply chain, at a local level in Italy, by focusing the analysis at the final stage of fish consumption, produced by Italian households. Among the causes, the change in consumption habits and attitudes is also influenced by the restrictions of the healthy regulations adopted for the pandemic. Specifically, a survey was conducted to investigate what actions, habits and behaviors contribute to producing fish food waste. Causes of waste have been discussed by framing them under two dimensions of final consumption, home consumption and out-of-home consumption. Findings carried out from the research suggest knowledge of channels of distribution and integrative elements to manage the leftover food as well as the intensity of fish consumption are basilar to understand the wastage mechanism in a circular perspective. This study is an assessment of whether factors identified as causes, may increase, or decrease the waste. The importance of realizing explorative studies at the consumption phase under the approach of considering fish waste, not only as a fraction into the food waste but even a distinct part as a whole, is also given by the need to create specific strategies for sustainable production and consumption. A reflection is conducted as to how this study can be the basis for future studies on other food products related to the challenge of the rational management of food waste studies in a circular perspective.