(Weber and de Beaufort)
1. Distinctive characters of early developmental stages
(a) Eggs and Larvae
Often confused along with early developmental stages of related species I. elongata . Therefore, till date there is no authentic report about the identification of eggs and larvae of this species both from coastal and the mangrove environment.
(b) Early Juveniles (from the mangroves)
(Based on specimens measuring around 25 mm T.L.)
Ilisha kampeni 1
Body elongate and compressed. Depth of body 21% of standard length (In juveniles and adults the depth is 25 to 30% of S.L.). There are 21 prepelvic scutes and eight post pelvic scutes with a total of 29 scutes. The dorsal fin has 13 rays and the long anal fin contains 38 rays. Lower jaw longer than upper jaw and mouth is located upward. A dark black pigmentation is visible around the tip of the mouth in fresh specimens.
2. Distinguishing characters of similar species occurring in the mangroves
(a) Ilisha melastoma
Very rarely represented from the mangroves. (I. kampeni occurs frequently in mangroves). Juveniles alone occur in mangroves. (In the case of I. kampeni , most of the stages of life cycle (from early juveniles to adults) occur is mangroves). Body very deep with more than 30% of standard length. (In the case of I. kampeni , the body is not very deep with less than 30% of standard length). Scute count however overlaps with that of I. kampeni .
3. Salient biological characteristics
(a) Maximum size
197 mm (in marine environment); 177 mm (in mangrove environment).
(b) Food and feeding habits (in mangrove environment)
Mysids, sergestids, penaeid shrimp juveniles, amphipods, copepods, postlarval stages of prawns and shrimps and spicules of sponges in descending order of importance (Jeyaseelan, 1981).
(c) Reproductive biology
Based on juvenile recruitment studies, this species seems to breed throughout the year in south east Indian coast except during a brief period in north east monsoon (October - November) and early post monsoon (January - February). Fluctuations in seasons of breeding was noticed in this species during different years (Jeyaseelan, 1981).
4. Salient ecological information
(a) Habitat
A coastal species whose early juveniles and adults frequently occur in mangrove waterways. It is recorded from mangroves of south east India and Singapore. (Jeyaseelan, 1981; Gomez, 1980). The juveniles occur even in high turbid waters (more than 400 g/m^3 seston content) in the mangroves. The osmoregulatory capacity of the juveniles makes the species to dwell in wide range of salinity from mixo-mesohaline to mixo-euhaline conditions in different zones of the mangroves (Jeyaseelan, 1981).
(b) Geographic distribution
East coast of India, Indo-Malayan archipelago and Indonesia.
(c) Behaviour
A shoaling fish feeding principally on macro-zooplankters and benthic crustaceans in the mangroves.
5. Evolutionary significance
This species belongs to the subfamily Pristigasterinae, which comprise peculiar genera of clupeoids such as Opisthopterus (with no pelvic fin) and Raconda (with no pelvic and dorsal fins).