Abstract: A heat exchanger containing a plurality of spaced-apart plate pairs, where each plate pair defines a flow passage for the flow of a first fluid. In addition, one or more fins are thermally coupled and sandwiched by the spaced-apart plate pairs for flow of a second fluid. And, a fluid manifold that is fluidly coupled to the spaced-apart plate pairs at a manifold end of the spaced-apart plate pairs is provided. Further, a tab that extends from a flange end of a first plate of the first plate pair and in contact with a second tab extending from a flange end of a second plate of a second plate pair for providing a fluid flow blocker. Also, provided is a heat exchanger assembly containing a housing and the heat exchanger described herein.