Thryssa dayi, the Day's thryssa, is a species of ray-finned fish in the family Engraulidae. It is found in the Western Indian Ocean.

Size
This species reaches a length of .

Etymology
The fish is named in honor of Francis Day (1829–1889), the Inspector-General of Fisheries in India.

References

dayi
Taxa named by Thosaporn Wongratana
Fish described in 1983
Fish of the Indian Ocean