Fishes like sardine, Mackerel,Anchovies, Prawns, etc have the shoaling behavior,this is a collective behavior by fish These shoal can become huge, moving along coastlines and migrating across open oceans.

Fish shoals are locally termed as meenpulappu by local fishermen. In traditional practice, fishermen can identify fish shoals from a distance by eye sight. Traditionally fish shoals were identified by ocean color, waves, bubbles, jumping of fish or flocks of birds hovering over the shoal etc. From the movement of water and color of the sea, fishermen can guess the type of fish and their characteristics.Fish shoal was mainly detected by color of the water. Presence of dark patches in the water with ripples indicates a good catch of Mackerel. Dark blue patches or black color appear on the surface of water indicates a big shoal of Sardine. White color indicates Silver Pomfret or Silver belly. Red color indicates ‘veluri/kera/lizard fish. Muddy water indicates good catch.