A blood treatment device, in particular a dialyzer, configured to carry out a blood treatment, in particular a dialysis treatment, or a device configured for the filling of a mobile apparatus with and/or for the emptying of a mobile apparatus of a treatment fluid, in particular a dialysis fluid is provided. The device has at least one mount which is made such that a mobile apparatus can be received in the mount. The device has a guide element and/or a fixing element which are designed such that the mobile apparatus can be introduced into the mount and/or fixed in the mount with the aid of the guide element and/or of the fixing element.
