The article is attempting to describe the design drawings we were shown, and without the visuals, it is hard to picture what exactly the information means. These designs will be available online soon according to the project management. From the presentation it was quite clear that the engineering design is professional and has been modified to include both fish ladders and sediment gates at the base of the dam.
The fish ladder has both an upstream and downstream navigation passage - the black/red arrows referred to in the article. This portion was designed by a European firm claiming the best currently available technology for fish passage.
I do not remember this comment about a 2 meter long fish. In fact, I remember instead a statement that with the sonar monitoring capacity, they would not miss a giant catfish - a species said to be in excess of 2 meters.