This paper is concerned with a novel problem of underwater cooperative transportation of multiple fishlike robots. A situation based action selection mechanism is proposed for the robots to transport a floating object to its destination. There are various control methods for cooperation of multi-robot system, but few of them deal with the underwater applications. In this paper, we first present the development of a series of biomimetic fish-like robots. Then, employing these robotic fish, we design and implement a cooperative transportation task utilizing a situation based action selection approach. We fully implement our method on three fish-like robots and make various experiments in a lab environment