You might want to use the consignment functionality to manage inventory you don't own

https://www.odoo.com/documentation/saas-18.4/applications/inventory_and_mrp/inventory/shipping_receiving/daily_operations/owned_stock.html

Hi,

Create each fish batch as a storable product in Inventory, then manually update quantities when received. When processing, use Manufacturing Orders to transform raw fish into finished products, then sell to customers via Sales Orders. Enable lot/serial tracking to maintain traceability from receipt through processing to delivery. For billing, create invoice lines for both the raw material (at zero value) and your processing fees, allowing you to generate complete invoices while avoiding traditional purchase workflows.

Key advantages:

       * Eliminates purchase orders while maintaining traceability

       * Manual quantity updates give you full control

       * Manufacturing orders handle processing specifications

       * Clean financial separation between materials and services

Sample Setup for Your Seafood Processing

1- Product Configuration

          - Raw Fish: Create as Storable Product with:

                    * Tracking: Lots (for traceability, e.g., "Boat123-Oct5")

                    * Cost: $0 (since you don’t purchase it)

                    * Routes: Disable Buy (no PO needed)

           - Processed Fish: Set as Manufactured Product with a BoM (Bill of Materials) linking to raw fish.

2- Receiving Fish (Manual Inventory Update)

        - Go to Inventory → Operations → Inventory Adjustment:

                 - Add raw fish product, assign a lot (e.g., fisherman’s name/date), and input received weight/quantity.

                 - Use "Scrap" or "Internal Transfer" to move to a "Holding Area" location.

3- Processing (Manufacturing Order)

              - Create Manufacturing Order:

                         * Select the Processed Fish product and BoM.

                         * Allocate raw fish lots (traceability preserved).

                         * Add Operations (e.g., "Fillet", "Freeze") with labor/time tracking if needed.

4- Selling & Invoicing

            - Create Sales Order for the customer:

                      * Add Processed Fish (priced per lb/kg) + Processing Fee (service product).

                      * Use Delivery to confirm pickup (no shipping needed).

            - Invoice: Combines product + service fees automatically.

Hope it helps