Woodlouse puffer fish
| Woodlouse puffer fish | ||||||||||||
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Woodlouse puffer ( Colomesus asellus ) |
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| Scientific name | ||||||||||||
| Colomesus asellus | ||||||||||||
| ( Müller & Troschel , 1848) |
The Assel pufferfish ( Colomesus asellus , Syn. : Chelychthis asellus ) is in South America in the Amazon Basin , in western Brazil , in Rio Purus , in western Guyana , Peru and Colombia beheimateter freshwater blowfish . It lives there in floodplain lakes in water depths of up to 60 cm. Until the first description of Colomesus tocantinensis (2013), the woodlouse puffer was the only freshwater puffer fish in South America.
features
The woodlouse puffer fish can reach a body length of up to 12.8 cm SL . There is a distinct, large black spot on the underside of the tail stalk.
Müller and Troschel described the species as Chelychthis asellus as follows and gave the fin formula D 10, A 9, P 15, C 9:
“ Rough back and stomach, muzzle, tail and a strip on the side of the back smooth, only close behind the eye do the roughness of the back and stomach unite. Above six dark transverse bands, the first on the muzzle, the second between the eyes, the third between the eyes and pectoral fins, the fourth broadest close behind the pectoral fins, the fifth at the beginning of the dorsal fin, the sixth in front of the caudal fin. The base of the pectoral fin, a spot under the tail, and the back half of the caudal fin are also black. The dorsal fin stands above the anal fin. Size 4 inches (10.16 centimeters). "
Colomesus asellus differs from the brackish water or seawater species Colomesus psittacus in the number of dark transverse bands between the eye and the tail stalk. This has Colomesus psittacus six Colomesus asellus but only five. Furthermore, Colomesus psittacus has 17 to 19 and Colomesus asellus 13 to 16 rays in the pectoral fin. Only in Colomesus asellus are a number of skin flaps across the chin, which are absent in Colomesus psittacus and Colomesus tocantinensis . The dark spot on the underside of the tail peduncle of Colomesus asellus may be present or absent in Colomesus tocantinensis .
habitat
In Lago Camaleo, a floodplain near Manaus (Brazil), two teams of scientists (Furch 1983, Soares 1986) studied the habitat and diet of Colomesus asellus . The lake has a high concentration of oxygen, which drops rapidly in the dry season when the natural influx is interrupted. During these dry periods, the salt concentration increases sharply. Colomesus asellus is relatively common in the murky and clear rivers of the Central Amazonian Region, but not found in the Rio Negro. In the wild, the temperature in its natural biotope is rarely below 27 ° C.
nutrition
Like other puffer fish, Colomesus asellus has four tooth plates with which hard-shelled prey can be bitten. However, according to a study to characterize the fish species in the upper and middle Rio Tocantins basin, the species feeds on land and aquatic insects, fish, sediments, organic matter and algae. Another study was done on the riverside in upper-middle Tocantins. Diverse food resources are available there, which can vary spatially and seasonally. Despite the varied diet, juveniles and adult specimens mainly consumed mayflies nymphs in both the rainy and dry seasons , which characterizes the species as an insect eater. In a nutritional study by Soares in 1986, algae growth, insect larvae, molluscs, shrimps and parts of the fins of fish were found in the stomach of animals.
Reproduction
Araujo-Lima et al. (1994), examined the reproductive habits of Colomesus asellus , in which the animals leave the lakes at the onset of the rainy season and the associated flooding and go to the Amazon to spawn . A higher oxygen supply is presumably guaranteed here, while in the floodplain lakes the eggs would sink into the oxygen-poor substrate and the larval development would be inhibited. Colomesus asellus does not maintain brood and belongs to the free spawners . The species is very productive because its spawning behavior results in high losses. The small size of the fish larvae suggests that the eggs are small, similar to that of the marine puffer fish. The larvae go through a planktonic phase and are washed away by the currents in more distant floodplain lakes. The reproductive instinct is probably stimulated by the rapid dilution of the onset of rain at the beginning of the flood. Due to the increase in the salt content, the origin of which has not yet been clarified, the water has a very high potassium content .
Aquaristics
In contrast to many other puffer fish, it is not considered to be particularly aggressive and can therefore be kept in the community tank under certain circumstances. In the adult stage, however, the animals often become very rough towards other conspecifics. Fin-biting cannot therefore be completely ruled out. If he does not receive shellfish in the aquarium hobby, these teeth become so long that they shut the animals' mouths so that they ultimately starve to death. Catching with nets often ends with the death of the animals, as they suffocate faster than fish. Catch bells are preferable here. Colomesus asellus is considered to be very sensitive to oxygen. The animals lie on the ground during their resting phases. Colomesus asellus has an extremely large swimming instinct and, in contrast to other fish species, uses the anal fin, dorsal fin and pectoral fins as driving organs for locomotion.
Sources and further information
Individual evidence
- ↑ a b c Cesar RL Amaral, Paulo M. Brito, Dayse A. Silva, Elizeu F. Carvalho: A New Cryptic Species of South American Freshwater Pufferfish of the Genus Colomesus (Tetraodontidae), Based on Both Morphology and DNA Data. In PLoS One. 2013; 8 (9): e74397. PMC 3770603 (free full text)
- ↑ Fishbase
- ^ First description Müller, Troschel: Fish. In: Travels in British Guiana from 1840-1844. Executed by Richard Schomburgk. In addition to a fauna and flora of Guiana based on models by Johannes Müller, Ehrenberg, Erichson, Klotzsch, Troschel, Cabanis and others. Volume 3, p. 641. Online
- ↑ James C. Tyler (1964): A diagnosis of the two species of South American puffer fishes (Tetraodontidae, Plectognathi) of the genus Colomesus. In: Proc Acad Natl Sci Philad 116: pp. 119-148.
- ^ A b M. GM Soares, RG Almeida, WJ Junk: The trophic status of the fish fauna in Lago Camaleão, a macrophyte dominated floodplain lake in the middle Amazon. In: Amazoniana 4, 1986, pp. 511-526. ( Online )
- ↑ a b c Carlos A. Araujo-Lima, Daniel Savastano, Luciana Cardeliquio Jordão: Drift of Colomesus asellus, Larvae in the Amazonas river . (1994), in: Revue d´Hydrobiologie tropicale. Pp. 33-38. ( Online )
- ↑ Renata Bartolette et al. : Seasonal and ontogenetic diet patterns of the freshwater pufferfish Colomesus asellus (Müller & Troschel, 1849) in the upper-middle Tocantins River. In: Acta Scientiarum. Biological Sciences, v. 40, e35282, 2018. ( Online )
literature
- Junk, WJMG M Soares & FM Carvalho: Distribution of fish species in a lake in the Amazon river floodpain near Manaus (Lago Camaleao), with special reference to extreme oxygen conditions . (1983) Amazoniana 7 (4): 397-431.
- K. Furch: Seasonal variation in the major cation (Na, K, Mg, and Ca) content of the water of Lago Camaleao, an Amazonian floddpain-lake near Manaus, Brazil . (1983) Amazonia 8 (1): 75-89.
- Florian Groth: Amazonas, freshwater aquarium magazine (2007) (No.11: 34-36) .
Web links
- Assel pufferfish on Fishbase.org (English)
- www.thetropicaltank.co.uk