It looks like bony fish have a two-chambered heart with arteries, veins, and cappillaries. The immune system includes at least three diferent types of white blood cells B-cells which produce antibodies, macrophages the engulf bacteria and T-cells. Here is a quote about T-cells from a fish vaccine reasearcher.
"T-cells are co-ordinators of the immune system. When activated, they secrete interferons and interleukins, which jolt the B-cells and the macrophages into greater action. The activated T-cells recognize and kill any host cells that might be infected with a bacterium or virus. "
At least that is what I have found after a quick search.