(Tilesius)
1. Distinctive characteristics of early developmental stages
(a) Eggs and pro-larvae
Not yet recorded from the mangroves.
(b) Post-larvae (Based on 8.8 mm specimens)
Cociella crocodila 1
The head is large, dorsoventrally compressed, and the preoperculum has 2 spines. The mouth is large, but the interorbital space is very small (less than a quarter of the diameter of the eye). The ridge crossing the cheek below the eye has 3 minute spines. The body tapers towards the posterior part. Pectoral fins and pelvic fins are larger in proportion to the body length when compared to those in adults. The first dorsal fin has eight spines, the first one the smallest, the 3rd the largest and gradually reducing in length towards the last spine. The second dorsal and anal fins possess 11 rays. The first and second dorsal fins are yet to move posteriorly to reach their final position as in adults. Distinct pigmentation is absent in the caudal fin.
2. Distinguishing characteristics of early developmental stages in similar species occurring in adjacent brackish and coastal waters
(a) Post-larvae and early juveniles of Platycephalus indicus
The interorbital space is wider (about twice the diameter of the eye). Early juveniles possess distinct yellow coloured caudal fins with two or three horizontal black bands lined by a white edge.
3. Salient biological characteristics
(a) Maximum size
50 cm in length.
(b) Food and feeding
This fish is a carnivore, feeding on fish, shrimps and benthic organisms in brackish and coastal waters.
4. Salient ecological information
The larvae and juveniles of this species rarely enter the mangrove estuaries, especially the lower reaches. It is distributed widely throughout the Indo-Pacific region, and occurs in sandy and muddy areas near to the shore up to 100 metres in depth (Fischer and Bianchi, 1984). It is a benthic fish with restricted movement. However, the advanced post-larval form is sturdy and possesses enlarged pectoral and pelvic fins for better propagation. It has a relatively lower adaptability to fluctuating environmental variables than the Platycephalus indicus.