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| ( Ham. , 1822) |
Tor tor is a large carp fish that is found on the Indian subcontinent . The name is based on a vernacular term , namely the related " putitor ".
From a zoological point of view, it is a close relative of the species of the genus Barbus (to which it has been variously assigned because of its long barbels ), but with a greater preference for turbulent flowing water, so that in its homeland it is partly the place of the missing salmonids ( trout and grayling ).
Occurrence
Its home is the entire subcontinent from Pakistan to Bangladesh , including Nepal , Bhutan and Sri Lanka ; in the east, thanks to human aid, it has advanced to Malaysia and China, and in the northwest to Afghanistan. However, "reintroductions" in Japan did not work. In view of the large, heterogeneous distribution area, the exact delimitation of the species is still uncertain.
anatomy
Tor tor resembles both our barbel and - distantly - the jumping sea fish tarpon . He uses his jumping power to overcome waterfalls. The maximum lengths are currently 90 cm (age: up to 10 years): Reports from earlier times of 2 m long and almost 50 kg heavy specimens are credible. Females grow larger than males.
As one of very few fish, it always has only one row of scales over every two muscle segments, otherwise this ratio is more likely the opposite or at least 1: 1. A functional justification can hardly be found for this, reasons such as Darwin's sexual selection can only be guessed at. The color is silvery, but the fins can be red.
Fin formula : DI / 11, A 7–8, P 19, V 9, C 19. Ventral fin with basal axillary process. The strong dorsal spine is smooth. The sideline arches over 22–27 scales; There are 4.5 rows of scales on the back, 2.5 rows on the abdomen, and 9 scales in front of the dorsal fin.
The lips are thick and fleshy. When he opens his mouth, the "lips" are turned outward, with which he can scrape food off stones. Like all carp fish, it has no teeth in its jaw. But the "lips" are rough due to the corneal papillae, but there are very large differences depending on the population, including gender - they sometimes even appear hypertrophied (cf. the illustration). However, it is not true that such “lips” are a gender characteristic of females. The mouth, which is adapted to the intake of food from the bottom, helps the fish to attach themselves to the substrate in order to withstand strong currents. At the front and back of the upper jaw there is a long barb with a lot of tactile and taste organs. The nostrils and eyes are large (in some related species, the eyes are smaller). Tor tor has 100 chromosomes and is arguably tetraploid .
The pharyngeal teeth stand on the pharyngealia , as with all barbel, in three rows (from inside to outside: 5, 3, 2) - but, as with carp- like, they are always fused with them - they are not changed, but grow from them the basis further. As with most cyprinids, they work against a horny plate in the roof of the pharynx, which is supported by a bone process at the base of the skull. According to Hora (1940), fishermen often keep the pharyngealia as evidence of capital catches.
Tor tor has achieved some fame - he is e.g. B. probably the fish with the relatively largest scales. The scales are occasionally so large that playing cards were cut out of them in parts of Nepal .
Ecology and reproduction
Tor tor is a cold and warm water fish. It can live in rivers, lakes and reservoirs that are fed by melt water and can be found in warm lakes. Due to the temperature tolerance, the gate category is eurytherm . Tor tor is euryphagous - in addition to benthos (insect larvae, mollusks, crustaceans, worms) and plankton, it also eats algae from stones and rocks (blue, gold, diatoms, but also filamentous green algae, later also macrophytes - mainly because of of the snails living on it). Its main predators are several large species of catfish.
To spawn, it needs cool mountain streams, to which it rises before the start of the rainy season. However, obstructions are increasingly preventing it from doing so, so that breeding stations have gone into operation in many places. For the purpose of heterosis , species crossings that do not occur in nature are also tested there. Tor tor and similarly sized carp fish are not only welcome food fish, but are also intended to attract sport fishermen from all over the world.
It becomes sexually mature with a length of 30–40 cm (at age 2+ or 3+). But it is considered slow-growing and long-lived. During the spawning migration and until spawning, it shows little appetite. The spawning season is between March and September, depending on the region. Pearl organs ( spawning rash ) only show males on the head (forehead). A large female (75 cm) can lay around 136,000 eggs per season in up to four spawning actions, often followed by several males. The lemon-yellow eggs (2–3 mm in diameter) stick to stones or rocks. The yolk sac larva spends the first week of free life almost immobile in rubble or under stones. The fry develop well only with predominantly animal food ( copepods , mosquito larvae ).
Culture
At least in places, in the vicinity of many Hindu temples , the fish is considered sacred, is not caught, but fed and thus soon becomes tame and can be observed in schools . It is hailed as the "ultimate challenge for anglers" in tourism advertising, although it has already been extinct in many places. The International Union for Conservation of Nature and Natural Resources (IUCN) classifies it as low risk (NT, Near Threatened) due to the decreasing population.
swell
- Biology (VR Desai 2003): ftp://ftp.fao.org/fi/document/sidp/y4642e_Tortor/y4642e00.pdf . (PDF; 341 kB)
- Tor at Fishbase.org (English)
Individual evidence
- ^ VR Desai: Synopsis of Biological Data on the Tor Mahseer Tor tor (Hamilton, 1822 ). In: FAO Fisheries Synopsis No. 158, 2003, p. 1. ( Online )
- ^ VR Desai: Synopsis of Biological Data on the Tor Mahseer Tor tor (Hamilton, 1822 ). In: FAO Fisheries Synopsis No. 158, 2003, p. 8. ( Online )
- ^ Tej Kumar Shrestha: Resource Ecology of the Himalayan Waters: A Study of Ecology, Biology and Management Strategy of Fresh Waters. , Steven Simpson Natural History Books, 1986, ISBN 978-0952439028 , p. 288.
- ^ VR Desai: Synopsis of Biological Data on the Tor Mahseer Tor tor (Hamilton, 1822 ). In: FAO Fisheries Synopsis No. 158, 2003, p. 16. ( Online )
- ^ VR Desai: Synopsis of Biological Data on the Tor Mahseer Tor tor (Hamilton, 1822 ). In: FAO Fisheries Synopsis No. 158, 2003, pp. 1 and 21. ( Online )
- ↑ Tor tor in the Red List of Threatened Species of IUCN 2010.4. Posted by: A. Rayamajhi, BR Jha, C. Sharma, 2009. Retrieved December 21, 2010.
