![]() Ovarian follicle, briefly, then along full ovary length Via the coelomic cavity and pericardial sacĭermogenys pusilla from Sabah and Dermogenys orientalis Southeast Asian populations of Dermogenys pusilla Meisner and Burns identified no fewer than five distinct modes of viviparity and ovoviviparity in fresh and brackish water halfbeaks: Type However, there is a great deal of variation in the details. tengah ), that is, they produce well-developed free-swimming young. ![]() The fresh and brackish water halfbeaks of the genera Dermogenys, Hemirhamphodon, and Nomorhamphus are all livebearers (with the exception of the oviparous H. Members of the genus Zenarchopterus and presumably the poorly-known Tondanichthys are oviparous. Young fresh water halfbeak, Nomorhamphus sp., aged 7 days, approximately 18 mm (0.71 in) in length. Viviparous halfbeaks are more predatory than the marine species, and typically orient themselves into the current and take aquatic insect larvae, such as midge larvae, and small insects, such as flies that have fallen on the surface of the water, particularly mosquitoes and spiders. Notably, they feed extensively on female mosquitoes that are laying their eggs in the water, making them much better at mosquito control that species like guppies and mosquitofish that only take mosquito larvae. These non-schoolers prefer to lurk among aquatic plants such as reeds, dead trees, and artificial structures of various types from where they wait for small prey animals to drift by or alight on the surface, before darting from their hiding place to hunt. Viviparous halfbeaks vary in social behavior from open water schooling fish similar to the marine halfbeaks (family Hemiramphidae), as with species of Zenarchopterus, through to much more aggressive and combative fishes, as is best known from the "wrestling" halfbeaks of genus Dermogenys. The following genera are classified within the family Zenarchopteridae Several, such as the wrestling halfbeak, have become commonly traded aquarium fish. The members in the family are mainly found in fresh and brackish water of tropical Asia and New Guinea, but the genus Zenarchopterus also includes marine species from the Indo-Pacific. The Zenarchopteridae exhibit strong sexual dimorphism, practicing internal fertilisation, and in some cases ovoviviparous or viviparous (the family also includes oviparous species). Zenarchopteridae, the viviparous halfbeaks, is a family in the order Beloniformes. Female Dermogenys sumatrana a day or so before giving birth.
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