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Dwarf pufferfish | |
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An adult dwarf pufferfish | |
Scientific classification | |
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Genus: | |
Species: | C. travancoricus
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Binomial name | |
Carinotetraodon travancoricus | |
Synonyms[2][1] | |
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Dwarf pufferfish (Carinotetraodon travancoricus), also called Malabar pufferfish, pygmy pufferfish, or pea pufferfish, are small freshwater pufferfish. They live only in Kerala and southern Karnataka in Southwest India. They are popular in the aquarium hobby for their bright colours and small size. Dwarf pufferfish are one of the smallest pufferfish on Earth and their maximum size is 3.5 centimetres (1.4 inches). They look like Carinotetraodon imitator, which are also pufferfish. Until 1999, C. imitator were mistakenly believed to be dwarf pufferfish.
Dwarf pufferfish live at the bottom of streams or rivers with a lot of plant life. They eat small animals. Unlike other pufferfish, dwarf pufferfish live in large groups in the wild. They breed throughout most of the year, with parents laying 1-5 eggs every 1-4 days. Habitat loss and overharvesting for the aquarium trade threaten wild populations of dwarf pufferfish.
Taxonomy
changeThe dwarf pufferfish was first described as Tetraodon (Monotretus) travancoricus in 1941 by S.L. Hora and K.K. Nair, with the type locality given as "Pamba River, Central Travancore". Carinotetraodon was considered a synonym of Tetraodon until 1978, when J.C. Tyler treated it as a valid genus in a paper about Carinotetraodon lorteti, which was an opinion followed by M. Kottelat et al. in 1993 and K.K.P. Lim and M. Kottelat in 1995. The first use of "Carinotetraodon travancoricus" was in 1999 by R. Britz and M. Kottelat when first describing Carinotetraodon imitator, a superficially similar and closely related species previously mistaken for dwarf pufferfish. "Carinotetraodon" is derived from the Latin word "carina" (keel-shaped, shell) and Greek words "tetra" (four) and "odous" (teeth).[3] The justification for moving to Carinotetraodon was based largely on osteological evidence and not on the presence of skin keels, which other members of the genus have, but which had not been confirmed in dwarf pufferfish until one year later in aquarium literature.[4] Specifically, dwarf pufferfish possess vertebral modifications and a reduced number of total vertebrae similar to other members of Carinotetraodon, in addition to a small size and the presence of sexual dimorphism, also found amongst other members of this genus.[5]
Carinotetraodon is a polyphyletic genus, meaning members do not necessarily share an immediate common ancestor but have been grouped based on common characteristics. The following cladogram is based on molecular evidence and illustrates the polyphyletic nature of the genus Carinotetraodon:[6]
Tetraodontidae |
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Description
changeThe maximum documented size is 3.5 cm (1.4 in) total length (TL),[7] with individuals typically reaching less than 2.5 cm (0.98 in) TL,[3] making dwarf pufferfish one of the smallest pufferfish in the world.[8] Both sexes are primarily greenish-yellow, with dark green to brown-black iridescent patches on the flanks and dorsal surface. Patterns and colouration vary considerably between individuals. Their pectoral fins are short, fan-shaped, and described as "slightly emarginate", that is to say, slightly indented at the tip. The dorsal and anal fins are situated opposite each other toward the posterior of the fish, both short and round, while the caudal fin is larger than the other fins and truncate, in that it terminates in a more-or-less vertical edge. Their bodies are round and oblong.[1][9] As with other members of the genus, sexual dimorphism is apparent in mature fish, with males being more brightly coloured than females[8] and having a yellow ventral surface.[10] Males can also have a dark stripe down the centre of their pale belly and iridescent, blue "eye wrinkle" patterns that females do not have. Females are more rounded, tend to be larger than males, and may or may not show more small spots between their larger dark markings. Their abdomens are white, and they may have a yellow patch on their throat.[10]
Natural defenses
changeAll pufferfish can inflate their bodies by quickly ingesting large amounts of water (or air when necessary) into their highly elastic stomachs.[11] Like many other pufferfish, in the absence of scales, dwarf pufferfish also have skin spines on most of their body.[5][4][12] These spines become erect when the fish is inflated. These characteristics are anti-predator adaptations that make the fish difficult to swallow or bite. Biologists believe these adaptations evolved because of the slow swimming speeds of pufferfish.[11][13] As an exercise, pufferfish will occasionally inflate to stretch their stomachs to avoid injuring themselves when inflating under duress. Inflation is thought to be stressful and perhaps painful for the fish.[13]
Though many freshwater pufferfish accumulate saxitoxin in their organs due to their consumption of specific cyanobacteria present on or in their food sources, no research has been published confirming or denying the presence of this neurotoxin in dwarf pufferfish.[10]
Resemblance to Carinotetraodon imitator
changeCarinotetraodon imitator is a species of related pufferfish closely resembling dwarf pufferfish. They are of similar size, shape, patterns, and colouration. Both species are found within the same region and may be sympatric, possibly inhabiting the same waters. Until 1999, C. imitator was mistaken as the same species, and the two could be found together in aquaria and were widely available in the international aquarium trade, both sold as dwarf pufferfish. Dwarf pufferfish can be distinguished from their congener (a member of the same genus), as C. imitator have smaller, faint blotches compared to dwarf pufferfish, as well as greatly reduced body spination. Male dwarf pufferfish have a darker yellow colouration and an iridescent "eye wrinkle" not found in males of C. imitator.[5]
Distribution and habitat
changeAlthough closely related to marine pufferfish, they are not found in salt water, and reports to the contrary are based on misidentification.[14] Dwarf pufferfish are one of only 27 known species of Tetraodontidae known to be adapted to freshwater.[15] They are a migratory, or potamodromous, species[16][17] endemic to rivers, lakes, and estuaries[18] in Kerala and southern Karnataka in the Western Ghats of Peninsular India.[2][19][20] They can be found in waters with a pH ranging from 7.5–8.3 and temperatures ranging from 22–28 °C (72–82 °F).[17] Inhabiting heavily vegetated waters with beds of gravel and rock or clay loam with silt and sand,[18] the species is reported from 13 rivers in Kerala,[21] including Pamba River,[1] Chalakudy River,[22] Periyar, Kechery,[23] Muvattupuzha,[24] Vembanad, Meenachil River, Cherthala,[25] Nilambur harbours,[19] and Kallar Stream, part of the Neyyar Wildlife Sanctuary.[18] They have been reported as rare in Bharathapuzha[26] and the Nilgiri Biosphere Reserve.[27] The species was also found in inundated brickyards in Puthukkad,[23] as well as ditches, ponds, irrigation channels, and artificial tanks or abandoned water bodies in paddy fields. The expansive range of their distribution and their appearances in small, secluded bodies of water is likely mediated in part by piscivorous birds inadvertently dispersing individuals.[28]
During a 2007 field survey, dwarf pufferfish were found in abundance in heavily vegetated, shallow waters, sheltering under floating duckweed. Piscivorous waterfowl were also observed foraging in the waters "in good number". The birds were noted to be of "ubiquitous association" with the waters dwarf pufferfish inhabit, and that dwarf pufferfish also inhabit the Thattekad Bird Sanctuary. The researchers inferred the birds likely predate the dwarf pufferfish, but did not identify the particular bird species.[28]
Conservation status
changeSeveral researchers have considered the species endangered, though with no rationale provided.[29][30][22] The dwarf pufferfish is officially classified as vulnerable on the IUCN Red List due to declining populations because of damming, indiscriminate deforestation for agriculture, pollution from wastewater, and, primarily, overfishing for the aquarium trade.[2][21] In 2010, some researchers estimated that the population would decline by 30–40% from 2005 to 2015,[2][29] while others estimated it had already declined by the same amount between 2005 and 2010.[31]
Diet and behaviour
changeDwarf pufferfish are euryphagous carnivores in that they consume a wide variety of animals. The results of studies indicated dwarf pufferfish favour insect larvae but will rely on crustaceans and annelids as alternate feed when the availability of preferable prey decreases.[32] Their diet in the wild mainly consists of small animals such as Cladocera, rotifers, copepods, and Ostracods, and insects such as the larvae of Odonata, Ephemeroptera, Hemiptera, and Diptera, with some amounts of plant matter, largely diatoms and green algae.[18][32] Sand and detritus, presumably ingested by mistake when feeding on small, bottom-dwelling animals, have also been found in the gut of dwarf pufferfish.[18][32]
In captivity, dwarf pufferfish benefit from a varied diet and will eat small snails such as ramshorn snails, bladder snails, and Malaysian trumpet snails, as well as foods like bloodworms and brine shrimp, which can be fed live or frozen. Other members of the genus feed on zooplankton and various benthic crustaceans and molluscs.[33] Food items of specimens maintained in aquaria appear to be similar.[8] Dwarf pufferfish are commonly associated with plants in the genus Cabomba, and the presence of these plants has been shown to reduce mortality among captive specimens.[21]
Dwarf pufferfish are a slow-swimming,[28] demersal, or bottom-dwelling, species.[16][17] Unlike many pufferfish species, which are primarily solitary and potentially aggressive or territorial between conspecifics (members of the same species),[34] dwarf pufferfish are found in large shoals, occasionally consisting of hundreds of individuals.[23] They are found mainly during the summer months (January to May) and rarely during the rainy season.[23] Shoaling fish are known to experience stress or weight loss when kept in solitude or in groups too small.[35][36]
Reproduction
changeIn the wild, males with ripe gonads have been found during all months of the year but December and January, with the peak spawning period extending from May to August, concurring with the South-West monsoon period.[37] Within the Pamba River, the minimum size at which half the population becomes sexually mature is approximately 1.83 cm (0.72 in). Environmental and dietary conditions may influence the maturation rate of individuals.[37]
The mid-dorsal and mid-ventral skin ridges of males become brown in colour during the spawning season. The belly of the female will swell, and the courting male will frequently chase the female and nibble at its belly. The female will then search for a suitable location to spawn while the male chases away other males.[15] In the aquarium, dwarf pufferfish are often plant-spawners, laying eggs in plants, including java moss, or on the substrate hidden within plants.[38] A female will scatter approximately 1–5 eggs, 1.43 mm (0.056 in) in mean diameter. The eggs are adhesive and appear transparent and round, with a mass of small oil globules. After laying, the eggs are then fertilized externally by the male.[15] Spawning has been observed in the evening, with the female resting on the spawning site and the male slowly approaching. After spawning, both fish will leave the site. The male will then quickly return to guard the eggs.[15] Sneaking ejaculation by other males has also been observed.[15] The pair may spawn multiple times in 1–4 day intervals.[15]
Eggs hatch after five days at 27 °C (81 °F), with larvae and fry initially fed infusoria, Brachionus, frozen bloodworms, and brine shrimp when they are a week old.[38][15] There is little information on what the larvae eat in the wild.[8] Hatched larvae are a mean of 3.15 mm (0.124 in) TL, with eyes incompletely developed and the body a red-brown. The yolk sac is consumed in four days, and the larvae commence swimming after six days, at which point their eyes are completely developed.[15]
There is no information available on the lifespans of these fish in the wild, but aquarists report specimens will live for approximately five years in captivity.[10]
Association with humans
changeWhen first described in 1941, K. Nair noted that dwarf pufferfish were a favourite of children, who would catch and use the fish as playthings.[1] They were regarded as "frog tadpoles" by local fishermen[23] and otherwise given little consideration. They are of no interest to fisheries,[7] are not a food fish, and are only valued as ornamental fish in aquaria.[39][2] Dwarf pufferfish have become popular as aquarium fish thanks to their attractive colours, small size, "puppy dog eyes", and relative ease of maintenance.[8][40][32] The dwarf pufferfish is also one of the few aquarium fish to regularly eat small, live snails and thus can be helpful in controlling snail populations.[9]
Notes
changeReferences
change- ↑ 1.0 1.1 1.2 1.3 1.4 Hora, S.L.; Nair, K.K. (1941). "New records of freshwater fish from Travancore". Records of the Indian Museum. 43: 387–393. Retrieved 4 May 2022.
- ↑ 2.0 2.1 2.2 2.3 2.4 Dahanukar, N. (2011). "Carinotetraodon travancoricus". IUCN Red List of Threatened Species. 2011: e.T166591A174788004. doi:10.2305/IUCN.UK.2011-1.RLTS.T166591A174788004.en. Retrieved 4 May 2022.
- ↑ 3.0 3.1 Froese, Rainer and Pauly, Daniel, eds. (2017). "Carinotetraodon travancoricus" in FishBase. January 2017 version.
- ↑ 4.0 4.1 Britz, R.; Ali, A.; Philip, S.; Kumar, K.; Raghavan, R. (October 2012). "First record from the wild of Carinotetraodon imitator in Peninsular India (Teleostei: Tetraodontiformes: Tetraodontidae)". Ichthyological Exploration of Freshwaters: An international journal for field-orientated ichthyology. 23 (2): 105–109. ISSN 0936-9902. Retrieved 1 May 2022.
- ↑ 5.0 5.1 5.2 Britz, R.; Kottelat, M. (May 1999). "Carinotetraodon imitator, a new freshwater pufferfish from India (Teleostei: Tetraodontiformes)". Journal of South Asian Natural History. 4 (1). Sri Lanka: Wildlife Heritage Trust of Sri Lanka: 39–47. ISSN 1022-0828. Retrieved 19 May 2022.
- ↑ Sathyajith, C.; Yamanoue, Y.; Yokobori, S.; Thampy, S.; Vattiringal Jayadradhan, R.K. (December 2019). "Mitogenome analysis of dwarf pufferfish (Carinotetraodon travancoricus) endemic to southwest India and its implications in the phylogeny of Tetraodontidae". Journal of Genetics. 98 (5): 98–105. doi:10.1007/s12041-019-1151-9.
- ↑ 7.0 7.1 Talwar, P. K.; Jhingran, A.G. (1991). Inland fishes of India and adjacent countries. New Delhi: Oxford & IBH Pub. Co. ISBN 9788120406391.
- ↑ 8.0 8.1 8.2 8.3 8.4 Klaus Ebert (2001). The Puffers of Fresh and Brackish Water. Aqualog. pp. 19, 46–49. ISBN 3-931702-60-X.
- ↑ 9.0 9.1 Anna Mercy, T.V.; Gopalakrishnan, A.; Kapoor, D.; Lakra, W.S. (2007). Ornamental fishes of the Western Ghats of India. Lucknow: National Bureau of Fish Genetic Resources. pp. 227–228. ISBN 81-902951-8-7.
- ↑ 10.0 10.1 10.2 10.3 Hellweg, Mike (March 2007). "The Dwarf Puffer: A Pleasant Little Surprise". www.tfhmagazine.com. TFH Magazine. Retrieved 5 May 2022.
- ↑ 11.0 11.1 "Pufferfish | National Geographic". www.nationalgeograph.orc. National Geographic. 12 March 2010. Retrieved 28 May 2022.
- ↑ Shono, T.; Thiery, A.P.; Cooper, R. L.; Kurokawa, D.; Britz, R.; Okabe, M.; Fraser, G.J. (September 2019). "Evolution and Developmental Diversity of Skin Spines in Pufferfishes". iScience. 19: 1248–1259. doi:10.1016/j.isci.2019.06.003. Retrieved 31 May 2022.
- ↑ 13.0 13.1 "Why do pufferfish "puff up"? | Seattle Aquarium". www.seattleaquarium.org. Seattle Aquarium. 11 January 2013. Retrieved 29 May 2022.
- ↑ Schäfer F. Brackish Water Fishes, p 34. Aqualog 2005, ISBN 3-936027-82-X
- ↑ 15.0 15.1 15.2 15.3 15.4 15.5 15.6 15.7 Doi, Hiroyuki; Sakai, Harumi; Yamanoue, Yusuke; Sonoyama, Takayuki; Ishibashi, Toshiaki (March 2015). "Spawning of eight Southeast Asian brackish and freshwater puffers of the genera Tetraodon and Carinotetraodon in captivity". Fisheries Science. 81 (2): 291–299. doi:10.1007/s12562-014-0842-7.
- ↑ 16.0 16.1 Froese, Rainer and Pauly, Daniel, eds. (2021). "Carinotetraodon travancoricusus" in FishBase. September 2021 version.
- ↑ 17.0 17.1 17.2 "Carinotetraodon travancoricus (Hora & Nair, 1941) Malabar pufferfish". www.fishbase.de. FishBase. Retrieved 5 May 2022.
- ↑ 18.0 18.1 18.2 18.3 18.4 Prasad, G.; Sabu, K.; Prathibhakumari, P.V. (2012). "The first report of the Malabar puffer, Carinotetraodon travancoricus (Hora & Nair, 1941) from the Neyyar wildlife sanctuary with a note on its feeding habit and length-weight relationship" (PDF). Journal on New Biological Reports. 1 (2): 42–46. ISSN 2319-1104. Retrieved 6 May 2022.
- ↑ 19.0 19.1 Easa, P.S.; Basha, C.C. (1995). "A Survey on the Habitat and Distribution of Stream Fishes in the Kerala part of Nilgiri Biosphere Reserve" (PDF). Kerala Forest Research Report. 104. Retrieved 6 May 2022.
- ↑ Devi, K.R.; Indra, T.J.; Raghunathan, M.B. (2000). "On a report of Tetradon (Monotretus) travancoricus, from south Kanara, Karnataka, India". Journal of the Bombay Natural History Society. 97 (3): 441–443. Retrieved 4 May 2022.
- ↑ 21.0 21.1 21.2 Anupama, K.M.; Harikrishnan, M. (2015). "Improved survival of Malabar puffer fish, Carinotetraodon travancoricus (Hora and Nair, 1941) in planted aquaria". International Journal of Environmental Sciences. 6 (1): 138–144. doi:10.6088/ijes.6016. ISSN 0976-4402. Retrieved 5 May 2022.
- ↑ 22.0 22.1 Raghavan, R.; Prasad, G.; Ali, A.P.H.; Pereira, B. (2008). "Fish fauna of Chalakudy River, part of Western Ghats biodiversity hotspot, Kerala, India: patterns of distribution, threats and conservation needs". Biodiversity and Conservation. 17 (13): 3119–3131.
- ↑ 23.0 23.1 23.2 23.3 23.4 Biju, C.R., C.R.; Thomas, R.K.; Ajithkumar, C.R.; George, M.J. (1999). "Occurrence of Tetraodon travancoricus (Hora and Nair) in the Chalakudy, Periyar and Kechery rivers, Kerala". Journal of the Bombay Natural History Society. 96 (1): 161. Retrieved 4 May 2022.
- ↑ Beevi, K.S. Jameela; Ramachandran, A. (26 September 2009). "Checklist of freshwater fishes collected from Ernakulam District, Kerala, India" (PDF). Journal of Threatened Taxa. 1 (9): 493–494. doi:10.11609/JoTT.o1559.493-4. Retrieved 4 May 2022.
- ↑ Devi, K.R.; Indra, T.J.; Emiliyamma, K. J. (1996). "On the Fish Collections from Kerala, Deposited in Southern Regional Station, Zoological Survey of India by NRM Stockholm" (PDF). Records of Zoological Survey of India. 95: 3–4. Retrieved 4 May 2022.
- ↑ Bijukumar, A.; Philip, Siby; Ali, Anvar; Sushama, S.; Raghavan, Rajeev (26 November 2013). "Fishes of River Bharathapuzha, Kerala, India: diversity, distribution, threats and conservation". Journal of Threatened Taxa. 5 (15): 4979–4993. doi:10.11609/JoTT.o3640.4979-93.
- ↑ Easa, P.S.; Shaji, C.P. (1997). "Freshwater fish diversity in Kera a part of the Nilgiri Biosphere Reserve". Current Science. 73 (2): 180–182.
- ↑ 28.0 28.1 28.2 Gopi, K.C.; Radhakrishnan, C. (2007). "Waterbird-Mediated Chance-Dispersal of Fishes: A Natural Process of Affecting Range of Distribution and Biogeography of Fishes" (PDF). Records of the Zoological Survey of India. 108 (1): 19–31. Retrieved 6 May 2022.
- ↑ 29.0 29.1 Dahanukar, Neelesh; Raut, Rupesh; Bhat, Anuradha (22 December 2003). "Distribution, endemism and threat status of freshwater fishes in the Western Ghats of India" (PDF). Journal of Biogeography. 31: 123–136.
- ↑ Thomas, K.; George, M.; Biju, C. (April 2002). "Freshwater Fishes of Southern Kerala with Notes on the Distribution of Endemic and Endangered Species". Journal of the Bombay Natural History Society. 99 (1): 47–53. Retrieved 4 May 2022.
- ↑ Kurup, B.M.; Manojkumar, T.G. (2010). "Central Marine Fisheries Research Institute". Indian Journal of Fisheries. 57 (1). India: Central Marine Fisheries Research Institute: 81–85. ISSN 0970-6011.
- ↑ 32.0 32.1 32.2 32.3 Renjithkumar, C.R.; Roshni, K.; Ranjeet, K. (24 September 2020). "Feeding ecology of the endemic freshwater puffer fish Carinotetradon travancoricus (Hora & Nair, 1941) in Western Ghats hotspot, India". International Journal of Aquatic Biology. 8 (5): 300–310. doi:10.22034/ijab.v8i5.922.
- ↑ Froese, R.; D. Pauly (eds.). "Food Items Reported for Carinotetraodon lorteti". FishBase. Retrieved 7 March 2007.
- ↑ Monks, Neale (December 2007). "In Search of the Peaceful Puffer". tfhmagazine.com. TFH Magazine. Retrieved 6 May 2022.
- ↑ Pagnussat, Natália; Piato, Angelo L.; Schaefer, Isabel C.; Blank, Martina; Tamborski, Angélica R.; Guerim, Laura D.; Bonan, Carla D.; Vianna, Mônica R.M.; Lara, Diogo R. (September 2013). "One for All and All for One: The Importance of Shoaling on Behavioral and Stress Responses in Zebrafish". Zebrafish. 10 (3): 338–342. doi:10.1089/zeb.2013.0867.
- ↑ "Coral fish stress out if separated from 'shoal-mates'". Manila Bulletin. Manila Bulletin Publishing Corp. 22 September 2016. Retrieved 13 May 2022.
- ↑ 37.0 37.1 Anupama, K.M.; Hari Sankar, H.S.; Rithin Raj, M.; Harikrishnan, M. (July 2019). "Reproductive Biology of Malabar Pufferfish Carinotetraodon travancoricus (Tetraodontidae)". Journal of Ichthyology. 59 (4): 545–554. doi:10.1134/S0032945219040027. ISSN 0032-9452. Retrieved 6 May 2022.
- ↑ 38.0 38.1 Ralph, Chris (2003). Practical Fishkeeping: Pufferfish, p. 61. ISBN 1-86054-233-6
- ↑ Ponniah, A.G.; Gopalakrishnan, A. (2000). Endemic fish diversity of Western Ghats (PDF). Lucknow, India: National Bureau of Fish Genetic Resources. pp. 13–32. ISBN 81-901014-2-0. Retrieved 5 May 2022.
- ↑ Wenzel, R. (2004). Carinotetraodon travancoricus. Die Aquarien- und Terrarienzeitschrift 1/2004:36-37
External links
changeCategory:Carinotetraodon Category:Fishkeeping Category:Fish described in 1941 Category:Taxa named by Sunder Lal Hora Category:Endemic fauna of the Western Ghats Category:Freshwater fish of India Category:Species endangered by the pet trade Category:Species endangered by agricultural development Category:Species endangered by urbanization Category:Species endangered by damming Category:Species endangered by deforestation