Is fishing in government-prohibited areas, such as a dam on the Euphrates River within a government-controlled zone, considered unlawful (haram) or lawful (halal)?

It is permissible for the ولي الأمر (ruler/guardian) to prohibit hunting (or any other permissible act) if it serves a legitimate Islamic interest. These are some of the guiding principles:

1. Preventing Harm: If hunting leads to harm or something forbidden, such as prohibiting fishing during a specific period to protect fish stock, this falls under the rule of "preventing harm and causing harm." 2. Regulating Public Facilities and Funds: The state has the right to regulate permissible matters in which Muslims share (such as water, pasture, and hunting) to achieve justice and public interest. It has the authority to mandate or prohibit in this regard, just as the Prophet, peace be upon him, and Umar, may Allah be pleased with him, did in protecting certain areas and regulating routes. 3. Implementing Communal Obligations (Furood al-Kifayah): If communal obligations are entrusted to the state (such as Zakat (definition) and Jihad), it has the right to enact necessary regulations, whether by compulsion or prohibition, to fulfill them, such as conscription for Jihad and setting times for collecting Zakat.

Therefore, it is not permissible to disregard the state's prohibition on fishing for specific types of fish during the prohibited period, due to the benefits involved and the prevention of harm.