Visual pigment was extracted from a fresh water toleost,
Etroplus suratensis and the optical density measured over a range of 300–650 nm. The absorption spectrum indicates the
max
at 550 nm and a small hump at 530 nm. Through partial bleaching at 630 nm, it was confirmed that the fish possesses a mixture of 2 visual pigments: the one with the
max
at 550 nm predominating over the other.