Fig. 1
From: Beyond planar: fish schools adopt ladder formations in 3D

Fish schools adopt 3D formations both in nature and in the laboratory. Schools of (A) bluefin tuna and (B) pacific herring in 3D formations. (C–D) A small school of three giant danios with a pair (red and yellow dots) in an apparent (C) inline and (D) staggered formation when viewed from above. However, both had a significant vertical separation.