Danionella
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| Danionella | ||||||||||||||
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| Danionella translucida Roberts, 1986 |
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Danionella mirifica |
Danionella is a genus comprising the danionin species D. mirifica and D. translucida, two of the smallest freshwater fishes.
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[edit] Distribution
Both species of Danionella originate from Myanmar. D. translucida is described from the Ayeyarwady River basin, and D. mirifica was described from the Kaiming area in upper Myanmar.[1]
[edit] Description
When first described, Danionella translucida was the smallest ostariophysan and the smallest adult vertebrate to inhabit fresh water.[2] Its adult size ranges from 10–12 millimetres (.43–.47 in) SL.[2] D. mirifica gets slightly larger, at about 14 mm (.55 in) SL, but is still one of the smallest freshwater fishes.[1][3]
Danionella species lack scales, barbels, and lateral line.[2]
Observed in life, D. translucida is almost perfectly transparent except for its eyes. It has a distinctive pattern of melanophores. There are no melanophores on the dorsal surface except on the head over the posterior part of the brain. On the posterior half of the body, there a few melanophores following the horizontal midline. The sides and underside of the abdomen have melanophores. A double row of melanophores is present on the underside of the fish from the isthmus of the gills to the pelvic fins.[2] D. mirifica can be differentiated with its melanophores; in D. mirifica, there is only a single row of melanophores between the pelvic fins and the tips of the cleithra, and there is a lack of melanophores on the underside of the abdomen.[1]
Eggs in D. translucida has been found to range in size from about .3–.6 mm (.011–.024 in) in diameter, with ripe eggs being at least .5 mm (.019 in) in diameter. Females carried anywhere from 3 to 8 or 10 eggs. Compared to the body of the fish, these eggs are relatively large.[2]
[edit] Ecology
D. translucida was collected from the roots of floating aquatic plants in a slow-flowing, shallow stream (maximum depth 1 m) in the Pegu Division of Myanmar. It was found alongside Danio, Microrasbora, Erethistes, and Oryzias species.[2]
[edit] External links
[edit] References
- ^ a b c Britz, Ralf (October 2003). "Danionella mirifica, a new species of miniature fish from Upper Myanmar (Ostariophysi: Cyprinidae)" (PDF). Ichthyol. Explor. Freshwaters 14 (3): 217–222.
- ^ a b c d e f Roberts, Tyson R. (1986). "Danionella translucida, a new genus and species of cyprinid fish from Burma, one of the smallest living vertebrates" (PDF). Environmental Biology of Fishes 16 (4): 231–241. doi:.
- ^ "Danionella mirifica". FishBase. Ed. Ranier Froese and Daniel Pauly. July 2007 version. N.p.: FishBase, 2007.
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