Mojarras and silver-biddies are the common names used for the members of Gerreidae family. They often occur near the bottom in coastal waters of most tropical seas. They are mainly saltwater fishes but can also occur in brackish water and sometimes freshwater. They are recognized as small silvery fishes with terminal and highly protractile mouth. Their scales are large, obvious but deciduous.
Mojarras are often found in coastal lagoons and estuaries with sandy or muddy bottoms near mangroves. They can be found in school, small group or singly. They feed on small invertebrates gleaned from the bottom by taking up mouthfuls of substrate and expelling sand and debris.
There are 7 genera and about 51 species of Gerreidae worldwide. Malaysia has 2 genera and about 9 species.
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Scientific Name: Gerres erythrourus (Bloch, 1791) English Name: Deep-bodied Mojarra, Deep-body Silver-biddy French Name: Blanche elévée Mandarin Name | 鱼类中文名: 胶把 (Jiāo bǎ), 短钻嘴鱼 (Duǎn zuān zuǐ yú) Local Malay Name: Ikan Kapas-kapas, Kekapas, Kapas Laut, Kapas Sungai Thai Name | ชื่อสามัญภาษาไทย: ปลาดอกหมากครีบสั้น (Plād xk h̄māk khrīb s̄ận) Local Hokkien: Ka Pak Main Identification Features: Dorsal and anal fin spines strong, particularly second anal fin spine. Caudal fin strongly forked but short, and lobes broadly rounded without pointed tips. Dorsal fin edged with black. Trailing edge of caudal fin dusky. Anal and pelvic fins yellowish. Size: Maximum total length about 30 cm, commonly to 20 cm. Habitat and Ecology: Coastal waters, to 40 m depth. Form schools on sandy bottoms. Feeds on zooplankton, worms, bivalves, crustaceans and small fishes.  Scientific Name: Gerres filamentosus Cuvier, 1829 English Name: Whipfin Mojarra, Whipfin Silver-biddy, Long-rayed Mojarra French Name: Blanche fil Mandarin Name | 鱼类中文名: 胶把 (Jiāo bǎ), 曳丝钻嘴鱼 (Yè sī zuàn zuǐ yú) Local Malay Name: Ikan Kapas-kapas, Kekapas, Kapas Laut, Kapas Filamen Thai Name | ชื่อสามัญภาษาไทย: ปลาดอกหมากกระโดง (Plād xk h̄māk kradong) Local Hokkien: Ka Pak Main Identification Features: Second dorsal-fin spine laterally compressed, produced into a filament. Anal, caudal, pectoral, and pelvic fins dusky hyaline, tips of anal fin, lower lobe of caudal and pelvic fins white. Size: Maximum total length about 30 cm, commonly to 15 cm. Habitat and Ecology: Shallow coastal waters, estuaries and rivers, to 50 m depth. Often found in schools on sandy bottoms. Feeds on small organisms such as crustaceans, polychaetes, and foraminiferans on sand or muddy-sand bottoms.  Scientific Name: Pentaprion longimanus (Cantor, 1849) English Name: Longfin Mojarra, Longfin Silver-biddy French Name: Blanche à pagaies Mandarin Name | 鱼类中文名: 胶把 (Jiāo bǎ), 长臂钻嘴鱼 (Cháng bì zuǎn zuǐ yú) Local Malay Name: Ikan Kapas, Kapas-kapas, Kekapas, Kapas Kaca Thai Name | ชื่อสามัญภาษาไทย: ปลาดอกหมากครีบยาว (Plād xk h̄māk khrīb yāw) Local Hokkien: Ka Pak Main Identification Features: Anal fin base longer than base of the soft portion of dorsal fin. Colour silvery, with a mirror-like stripe from snout to caudal peduncle. Size: Maximum total length almost 20 cm, commonly to 10 cm. Habitat and Ecology: Coastal muddy-sand bottoms, to 70 m depth. Often form large schools. Feeds on small benthic invertebrates. 
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