Is it permissible for a commercial broker who receives a commission for mediating the sale of fish to add his commission to the purchase price and inform the buyer of the total price, or must the buyer determine the commission himself?

Commercial mediation has two scenarios:

1. If the institution's function is solely brokerage, and it has no relation to the profit or loss of the merchandise, then it is only entitled to a specified fee. It is not permissible to add this fee to the purchase price, lest it lead to its (the fee's) unknown quantity, and an unknown fee invalidates the lease (ijarah). 2. If the institution's function is to purchase goods, take possession of them, and then sell them to its customers, then it may add any desired profit to the purchase price, and it is then called profit, not commission.

What is understood from the question is that the institution's function falls under the first scenario, and in this case, it is not permissible to add the commission to the purchase price.