(Bleeker)
1. Distinctive characters of early developmental stages
(a) Eggs (Not recorded from the mangroves)
The size of the egg from plankton reported as 3.2 mm in diameter. Mature eggs in the ovary varied from 1.7 to 2.2 mm in diameter. (Bal and Rao, 1990)
(b) Larvae (Leptocephalus stage) (Not collected from mangroves)
Elongated, ribbon shaped and transparent; height relatively small and predorsal and post anal distances relatively shorter (when compared with M. cinereus ); 149 myomeres, 20 teeth in upper jaw and 17 in lower jaw; few chromatophores on the tip of the lower jaw; chromatophores in mid-lateral line begin from 23rd myomere; a few pigmented cells at the base of the anal fin. (Bal and Rao, 1990)
(c) Juveniles (based on 153 mm specimen from mangroves )
Congresox talabonoides 1
Elongated body without scales and pelvic fin; dorsal, caudal and anal fins continuous; pectoral fin length about 25% of head length; teeth on middle row of vomer needle-like and not blade-like and without any swollen bases.
(d) Distinguishing characters of early juveniles from those of adults
a) Lateral line pores before level of anus number only 34 (in the case of adults the pores vary from 41 to 42);
b) third row of teeth in lower jaw net yet developed (3 longitudinal rows of teeth in both jaws in adults);
c) teeth on middle row of vomer prominent but without any minute basal cusps (minute basal cusps seen in adults); and
d) the tooth row on lower jaw not leaning outwards (outer tooth row on lower jaw leaning outwards in adults).
2. Distinguishing characters of juveniles of similar species occurring ln the mangroves
(a) Muraenesox cinereus
Teeth on middle row of lower jaw and vomer, blade-like, triangular, laterally compressed and with prominent basal cusps in front and behind; inter-orbital width about 12.5% of head length; lateral line pores and dorsal fin rays before level of anus number 39 to 47 and 66 to 78 respectively.
(b) Muraenesox bagio
Teeth on middle row of lower jaw and vomer, blade-like, triangular, laterally compressed and with prominent basal cusps in front and behind; inter-orbital width around 9 to 10% of head length; lateral line pores and dorsal fin rays before level of anus number 33 to 39 and 47 to 59 respectively.
3. Salient biological characteristics
(a) Size:
Maximum length: 250 cm (Fischer and Bianchi, 1984).
(b) Food and feeding habits
This species exhibits nocturnal feeding behaviour. Adults feed on sciaenids, polynemids, engraulids, trichiurids and clupeids in order of preference (Bal and Rao, 1990). Cannibalistic; juveniles in mangroves feed principally on shrimps and gobioids.
(c) Reproductive biology
Spawning in the Indian seas twice a year with primary spawning during April-May and secondary spawning during September-October. Male/female sex ratio in Indian seas was observed as 1 : 0.6 during January, 1 : 4.9 in June and 1 : 2 during other periods of the year. Females mature at a minimum size of 122 to 125 cm whilst males at 117 cm. Fecundity ranged between 310,000 to 920,000 in specimens of 110 to 170 cm total length (Bal and Rao, 1990; Mohamed, 1955).
4. Salient ecological information
(a) Habitat
Juveniles inhabit estuaries and mangroves. Adults are marine, very common in the West Coast of India, especially along Maharashtra and Gujarat coasts and sporadic in the East Coast of India (Bal and Rao, 1990).
(b) Geographic distribution
Red sea; coasts of India; Malay archipelago; Indonesia; Philippines; Hong Kong and Taiwan (Fischer and Bianchi, 1984).
(c) Behaviour
Cannibalistic behaviour was reported in this species (Bal and Rao, 1990).
5. Capture fisheries and utilization
Undersized fishing has been carried out by cast-net, drag-net and state net in the mangrove waterways of South East India. Adults caught by long lines from the sea. Adults serve as useful food fish, iced and sent to interior markets. Airbladders are used in the preparation of isinglass.