(Broussonet, 1782)
1. Distinctive characters of early developmental stages
(a) Eggs
Not yet reported from the mangroves.
(b) Larvae (Leptocephalus stage) (After Delsman, 1926d)
Megalops cyprinoides 1
Larvae measure between 23 and 30 mm in length; ribbon-like transparent body; bifurcated tail; post anal myomeres considerably higher than in other leptocephalids belonging to the Elopiformes order (up to 17 nos.); air bladder situated below 29th myomere, ventral fin below 30th myomere and pre-anal myomeres are 51 in number.
2. Distinguishing characters of leptocephalus stages of similar species occurring in the mangroves
(a) Elops machnata
Air bladder below the 31st myomere (29th myomere in the case of M. cyprinoides ); Leptocephalus stage relatively larger than that of M. cyprinoides .
3. Distinguishing characters of leptocephalus stages of similar species from coastal waters
(a) Albula vulpes
Leptocephalus stage is the largest (64 mm maximum length) (in the case of Megalops cyprinoides , the corresponding stage is only half the size); anal fin located very closer to caudal fin with the least number of post anal myomere (more post anal myotomes - up to 17 in number - in the leptocephalus stage of M. cyprinoides ); ventral fin originates below 35th myomere (29 in the case of M. cyprinoides ); anal fin situated below the 67th myomere (51 in the case of M. cyprinoides ).
4. Distinctive characters of juveniles and adults
Gular plate present between arms of lower jaw; last of dorsal fin filamentous; eyes and scales are relatively larger than in related families.
5. Distinguishing characters of similar species occurring in the mangroves
(a) Nematalosa nasus
Last dorsal ray filamentous but no gular plate; eyes relatively small, mouth inferior; belly rounded with scutes; grows to the relatively small size of 245 mm only.
6. Salient biological characteristics
This species grows to a maximum size of 1 metre in total length in the seas. It is a carnivore, feeding on fishes, shrimps, acetes and other crustaceans. It is reported to mature at a size of 25 cm length and breeds twice a year in coastal waters (Santhanam et al., 1990).
7. Salient ecological information
It is a marine fish dwelling in brackish water and moving even as far as fresh water zones. It occurs in waters up to 40 ppt salinity (Santhanam et al., 1990).
8. Evolutionary significance
Closer ontogenic relationships exist among the family of this species (Megalopidae) with Elopidae and Albulidae.
9. Culture fisheries
It is considered as a candidate species for carnivorous fish culture in marine and brackish water environments. In fresh water culture systems, this species survives but the growth rate is not very promising. The species is suggested for polyculture along with Elops machnata (another carnivorous fish) with common prey organisms like Tilapia or any fish species capable of prolific breeding. In tidal fed coastal and brackish water shrimp farming, Megalops cyprinoides is considered as one of the most predator fish causing menace.