(Linnaeus)
1. Distinctive characteristics of early developmental stages
(a) Eggs and larvae
Not recorded from the mangroves.
(b) Early juveniles (description based on 30-34 mm T.L. specimens)
Monodactylus argenteus 1
Two dark vertical stripes are present, of which one runs between the upper and lower portions of the head through the eye and the other one runs from the nape to the pelvic fin base via the posterior border of the operculum and the pectoral fin base. Paired pelvic fins are present at this stage and their length measures as high as 8% of the standard length (as the fish grows, the pelvic fins disappear).
The dorsal fin has 7 spines and 30 rays and the spines are relatively longer in early juveniles than in adults. The height of the dorsal spines gradually increases from 1st to 7th (graduated) in early juveniles while the first six or seven spines are relatively very short and the last one is abruptly very long in adults. The anal fin has three spines and 28-32 soft rays.
2. Distinguishing characteristics of early stages in similar species occurring in the adjacent brackishwater / coral marine environment
(a) Juveniles of Monodactylus falciformis
11 to 12 vertical bars are present in young fish (only two vertical bars are present in the case of Monodactylus argenteus ).
3. Salient biological characteristics
This species grows to a maximum size of 230 mm in total length (Munro, 1955). It feeds on plankton and detritus (Fischer and Bianchi, 1984).
4. Salient ecological information
The juveniles of this species occur in estuaries and mangroves with less turbid waters. They move upstream, even as far as fresh water zones. This species occurs in coastal waters, coral environments and trawling grounds. It occasionally occurs in small schools in the mangroves. It is distributed throughout the Indo-Pacific region.
5. Capture fisheries and utilization
It is caught in shore seines in coastal waters and in cast-nets in brackish waters, including the mangroves and sold fresh in local markets, being subjected to processing if small in size. This species is of minor importance from the commercial fisheries point of view.
6. Culture fisheries
It is an excellent ornamental fish suitable for marine, brackish water and fresh water aquariculture. The early juveniles and juveniles possess brilliant vertical cross bars on a silvery background which makes them more attractive. This species (though occurring sporadically) is economically important in developing countries in earning foreign exchange through the setting up of aquariums/oceanariums in tourist spots and marine parks, interior decoration and for aquarium fish experts.
Besides the economic importance, it is also recreationally important in relieving the urban population from day to day stress, to aid the sick and enlighten children (by admiring the gift and beauty of nature).
Nowadays, the virgin or undisturbed mangroves and coral reef ecosystems have become picnic spots and tourist resorts in many tropical and sub-tropical regions of the world. If these ecosystems are not subjected to degradation in the long run due to anthropic interference (through stringent environmental protection measures), the setting up of small aquariums by utilizing such attractive species may boost the status of such recreational sports.