Dwarf pufferfish

The 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". The use of parentheses indicates Monotretus is the subgenus of Tetraodon. 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).{{FishBase |genus= Carinotetraodon |species= travancoricus |month=June |year=2023 }} 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. 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.{{cite journal |last1=Britz |first1=R. |last2=Kottelat |first2=M. |title=Carinotetraodon imitator, a new freshwater pufferfish from India (Teleostei: Tetraodontiformes) |journal=Journal of South Asian Natural History |date=May 1999 |volume=4 |issue=1 |pages=39–47 |url=https://www.researchgate.net/publication/267843168 |access-date=19 May 2022 |publisher=Wildlife Heritage Trust of Sri Lanka |location=Sri Lanka |issn=1022-0828}}

The following cladogram is based on molecular evidence and demonstrates the polyphyletic nature of the genus Carinotetraodon.{{cite journal |last1=Sathyajith |first1=C. |last2=Yamanoue |first2=Y. |last3=Yokobori |first3=S. |last4=Thampy |first4=S. |last5=Vattiringal Jayadradhan |first5=R.K. |title=Mitogenome analysis of dwarf pufferfish (Carinotetraodon travancoricus) endemic to southwest India and its implications in the phylogeny of Tetraodontidae |journal=Journal of Genetics |date=December 2019 |volume=98 |issue=5 |pages=98–105 |doi=10.1007/s12041-019-1151-9|pmid=31819020 |s2cid=208020436 }} A polyphyletic genus is one in which members share common characteristics, but do not necessarily share an immediate common ancestor, and their placement is based on these shared traits rather than confirmed, empirical evidence. "Carinotetraodon" is represented in quotation marks to signify its polyphyletic status. Freshwater species are denoted with "FW". The cladogram is incomplete due to the absence of species like C. imitator, which have not undergone mitogenome analyses.

File:Tetraodon nigroviridis 1.jpg

{{clade

|label1=Tetraodontidae

|1={{clade

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|1={{clade

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|1={{clade

|1=Auriglobus modestus

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|2={{clade

|1=Leiodon cutcutia^FW

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|2={{clade

|label1=

|1={{clade

|1="Carinotetraodon" salivator^FW

|2={{clade

|1="Carinotetraodon" lorteti^FW

|2="Carinotetraodon" irrubesco^FW

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|label2=

|2={{clade

|1=Pao palembangensis^FW

|2=Pao cochinchinensis^FW

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|2={{clade

|label1=

|1={{clade

|label1=

|1={{clade

|1="Carinotetraodon" travancoricus^FW

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|label2=

|2={{clade

|label1=

|1={{clade

|1=Dichotomyctere nigroviridis

|2=Dichotomyctere ocellatus

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|label2=

|2={{clade

|label1=

|1={{clade

|1=Pelagocephalus marki

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|label2=

|2={{clade

|label1=

|1={{clade

|1=Canthigaster coronata

|label2=

|2={{clade

|1=Canthigaster rivulata

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|2={{clade

|1=Canthigaster jactator

|2=Canthigaster valentini

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|3={{clade

|label1=

|1={{clade

|label1=

|1={{clade

|1=Chelonodon pleurospilus

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|2={{clade

|1=Chelonodon patoca

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|label2=

|2={{clade

|label1=

|1={{clade

|1=Tetraodon miurus^FW

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|label2=

|2={{clade

|1=Tetraodon mbu^FW

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File:Carinotetraodon travancoricus by Parazelsus (cropped).jpg

The maximum documented size is {{convert|3.5|cm|in|abbr=on}} total length (TL), with individuals typically reaching less than {{convert|2.5|cm|in|abbr=on}} TL, making dwarf pufferfish one of the smallest pufferfish in the world.{{cite journal |last1=Santini |first1=F. |last2=Nguyen |first2=M. T. T. |last3=Sorenson |first3=L. |last4=Waltzek |first4=T. B. |last5=Lynch Alfaro |first5=J. W. |last6=Eastman |first6=J. M. |last7=Alfaro |first7=M. E. |title=Do habitat shifts drive diversification in teleost fishes? An example from the pufferfishes (Tetraodontidae) |journal=Journal of Evolutionary Biology |date=May 2013 |volume=26 |issue=5 |pages=1003–1018 |doi=10.1111/jeb.12112 |pmid=23496826 |s2cid=25969423 |url=https://onlinelibrary.wiley.com/doi/full/10.1111/jeb.12112 |access-date=24 October 2023|url-access=subscription }}{{cite book |last=Klaus |first=Ebert |year=2001 |title=The Puffers of Fresh and Brackish Water |publisher=Aqualog |isbn=3-931702-60-X |pages=19, 46–49}} 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.{{cite journal |last1=Hora |first1=S.L. |last2=Nair |first2=K.K. |title=Notes on Fishes in the Indian Museum: XLI. New Records of Freshwater Fish from Travancore. |journal=Records of the Indian Museum |date=1941 |volume=43 |pages=387–393 |url=https://archive.org/details/records-indian-museum-43-387-393/page/n4/mode/1up |access-date=4 May 2022}} As with other members of the genus, sexual dimorphism is apparent in mature fish, with males being more brightly coloured than females and having a yellow ventral surface.{{cite magazine |last1=Hellweg |first1=Mike |date=March 2007 |title=The Dwarf Puffer: A Pleasant Little Surprise |url=https://www.tfhmagazine.com/articles/freshwater/the-dwarf-puffer-a-pleasant-little-surprise |access-date=5 May 2022 |website=www.tfhmagazine.com |publisher=TFH Magazine |language=en}} 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 have more small spots between their larger dark markings. Their abdomens are white, and they may have a yellow patch on their throat.

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All pufferfish can inflate, or "puff up", their bodies by quickly ingesting large amounts of water (or air when necessary) into their highly elastic stomachs.{{cite web |last1=Geggel |first1=Laura Geggel |title=Puffed-Up Blowfish Aren't Holding Their Breath |url=https://www.livescience.com/49010-pufferfish-breathe-during-inflation.html |website=livescience.com |publisher=Live Science |access-date=18 October 2023 |language=en |date=4 December 2014}} Inflating tires pufferfish and can put them at greater risk of predation. Like many other pufferfish, in the absence of scales, dwarf pufferfish have skin spines on most of their body.{{cite journal |last1=Britz |first1=R. |last2=Ali |first2=A. |last3=Philip |first3=S. |last4=Kumar |first4=K. |last5=Raghavan |first5=R. |title=First record from the wild of Carinotetraodon imitator in Peninsular India (Teleostei: Tetraodontiformes: Tetraodontidae) |journal=Ichthyological Exploration of Freshwaters|date=October 2012 |volume=23 |issue=2 |pages=105–109 |url=https://www.researchgate.net/publication/256202390 |access-date=1 May 2022 |issn=0936-9902}}{{cite journal |last1=Shono |first1=T. |last2=Thiery |first2=A.P. |last3=Cooper |first3=R. L. |last4=Kurokawa |first4=D. |last5=Britz |first5=R. |last6=Okabe |first6=M. |last7=Fraser |first7=G.J. |title=Evolution and Developmental Diversity of Skin Spines in Pufferfishes |journal=iScience |date=September 2019 |volume=19 |pages=1248–1259 |doi=10.1016/j.isci.2019.06.003 |pmid=31353167 |pmc=6831732 |bibcode=2019iSci...19.1248S }} These spines become erect when the fish is inflated. Dwarf pufferfish, like many other Tetraodontiformes, produce tetrodotoxin, a highly lethal neurotoxin for which there is no antidote.{{cite web |title=Tetrodotoxin: Biotoxin {{!}} NIOSH {{!}} CDC |url=https://www.cdc.gov/niosh/ershdb/emergencyresponsecard_29750019.html#:~:text=Initial%20treatment%20is%20primarily%20supportive.&text=There%20is%20no%20antidote%20for%20tetrodotoxin%20toxicity.&text=Remove%20the%20patient%2Fvictim%20from,order%20to%20avoid%20more%20casualties. |website=www.cdc.gov |access-date=12 May 2024 |language=en-us |date=25 May 2023}} The neurotoxin accumulates in the glands of the epidermis (surface layer of skin), ovaries, and livers of pufferfish.{{cite journal |last1=Lin |first1=W.-F. |last2=Hwang |first2=D.-F. |title=Analysis of Poisoning Cases, Monitoring and Risk Warning for Marine Toxins (TTX, PSP and CTXs) in Taiwan |journal=藥物食品分析 |date=1 January 2012 |volume=20 |issue=4 |pages=763–771 |doi=10.6227/jfda.2012200404 |url=https://www.jfda-online.com/cgi/viewcontent.cgi?article=2045&context=journal |access-date=12 May 2024 |language=en}} These traits are anti-predator adaptations. The pufferfish's ability to inflate makes it difficult to swallow or bite, and the tetrodotoxin makes it unpalatable or even deadly for other fish. Biologists believe these adaptations evolved because of the slow swimming speeds of pufferfish.{{cite web |title=Pufferfish {{!}} National Geographic |url=https://www.nationalgeographic.com/animals/fish/facts/pufferfish |archive-url=https://web.archive.org/web/20210329180151/https://www.nationalgeographic.com/animals/fish/facts/pufferfish |url-status=dead |archive-date=29 March 2021 |website=www.nationalgeograph.orc |publisher=National Geographic |access-date=28 May 2022 |language=en |date=12 March 2010}}

Carinotetraodon 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.

[[File:Dwarf pufferfish distribution map.svg|thumb|Global distributionBased on the following sources:

• {{cite journal |last1=Anupama |first1=K.M. |last2=Harikrishnan |first2=M. |title=Improved survival of Malabar puffer fish, Carinotetraodon travancoricus (Hora and Nair, 1941) in planted aquaria |journal=International Journal of Environmental Sciences |date=2015 |volume=6 |issue=1 |pages=138–144 |doi=10.6088/ijes.6016 |doi-broken-date=1 November 2024 |url=https://www.indianjournals.com/ijor.aspx?target=ijor:ijes&volume=6&issue=1&article=016 |issn=0976-4402}}
• {{cite journal |last1=Hora |first1=S.L. |last2=Nair |first2=K.K. |title=New records of freshwater fish from Travancore. |journal=Records of the Indian Museum |date=1941 |volume=43 |pages=387–393 |url=https://archive.org/details/records-indian-museum-43-387-393/page/n4/mode/1up |access-date=4 May 2022}}
• {{cite journal |last1=Raghavan |first1=R. |last2=Prasad |first2=G. |last3=Ali |first3=A.P.H. |last4=Pereira |first4=B. |title=Fish fauna of Chalakudy River, part of Western Ghats biodiversity hotspot, Kerala, India: patterns of distribution, threats and conservation needs |journal=Biodiversity and Conservation |date=2008 |volume=17 |issue=13 |pages=3119–3131|doi=10.1007/s10531-007-9293-0 |bibcode=2008BiCon..17.3119R |s2cid=7563806 }}
• {{cite journal |last1=Biju, C.R. |first1=C.R. |last2=Thomas |first2=R.K. |last3=Ajithkumar |first3=C.R. |last4=George |first4=M.J. |title=Occurrence of Tetraodon travancoricus (Hora and Nair) in the Chalakudy, Periyar and Kechery rivers, Kerala |journal=Journal of the Bombay Natural History Society |date=1999 |volume=96 |issue=1 |page=161 |url=https://archive.org/details/biostor-151846/mode/1up |access-date=4 May 2022}}
• {{cite journal |last1=Beevi |first1=K.S. Jameela |last2=Ramachandran |first2=A. |title=Checklist of freshwater fishes collected from Ernakulam District, Kerala, India |journal=Journal of Threatened Taxa |date=26 September 2009 |volume=1 |issue=9 |pages=493–494 |doi=10.11609/JoTT.o1559.493-4 |url=https://dyuthi.cusat.ac.in/xmlui/bitstream/handle/purl/4123/Checklist%20of%20freshwater%20fishes%20collectedfrom%20Ernakulam%20District%2c%20Kerala%2c%20India.pdf?sequence=1 |access-date=4 May 2022}}
• {{cite journal |last1=Devi |first1=K.R. |last2=Indra |first2=T.J. |last3=Emiliyamma |first3=K. J. |title=On the Fish Collections from Kerala, Deposited in Southern Regional Station, Zoological Survey of India by NRM Stockholm |journal=Records of Zoological Survey of India |date=1996 |volume=95 |pages=3–4 |url=http://faunaofindia.nic.in/PDFVolumes/records/095/03-04/0129-0146.pdf |access-date=4 May 2022}}
• {{cite journal |last1=Easa |first1=P.S. |last2=Basha |first2=C.C. |title=A Survey on the Habitat and Distribution of Stream Fishes in the Kerala part of Nilgiri Biosphere Reserve |journal=Kerala Forest Research Report |date=1995 |volume=104 |url=http://docs.kfri.res.in/KFRI-RR/KFRI-RR104.pdf |access-date=6 May 2022}}
• {{cite journal |last1=Prasad |first1=G. |last2=Sabu |first2=K. |last3=Prathibhakumari |first3=P.V. |title=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 |journal=Journal on New Biological Reports |date=2012 |volume=1 |issue=2 |pages=42–46 |url=https://researchtrend.net/jnbr/jnbr/VOL%201(2)%202012/3%20Prasad%20et%20al,%202012.pdf |access-date=6 May 2022 |issn=2319-1104}}
• {{cite journal |last1=Bijukumar |first1=A. |last2=Philip |first2=Siby |last3=Ali |first3=Anvar |last4=Sushama |first4=S. |last5=Raghavan |first5=Rajeev |title=Fishes of River Bharathapuzha, Kerala, India: diversity, distribution, threats and conservation |journal=Journal of Threatened Taxa |date=26 November 2013 |volume=5 |issue=15 |pages=4979–4993 |doi=10.11609/JoTT.o3640.4979-93|doi-access=free }}
• {{cite journal |last1=Easa |first1=P.S. |last2=Shaji |first2=C.P. |title=Freshwater fish diversity in Kera a part of the Nilgiri Biosphere Reserve |journal=Current Science |date=1997 |volume=73 |issue=2 |pages=180–182}}]]

Although closely related to marine pufferfish, they are not found in salt water, and reports to the contrary are based on misidentification.{{cite book |last1=Schäfer |first1=Frank |title=Brackish-water Fishes: All about Species, Care and Breeding |date=2005 |publisher=A.C.S. |isbn=9783936027822 |page=34}} Dwarf pufferfish are one of only 27 known species of Tetraodontidae adapted to freshwater.{{cite journal |last1=Doi |first1=Hiroyuki |last2=Sakai |first2=Harumi |last3=Yamanoue |first3=Yusuke |last4=Sonoyama |first4=Takayuki |last5=Ishibashi |first5=Toshiaki |title=Spawning of eight Southeast Asian brackish and freshwater puffers of the genera Tetraodon and Carinotetraodon in captivity |journal=Fisheries Science |date=March 2015 |volume=81 |issue=2 |pages=291–299 |doi=10.1007/s12562-014-0842-7|bibcode=2015FisSc..81..291D |s2cid=255616157 }} They are a potamodromous species,{{cite book |last1=Reid |first1=Klaus |title=Global Register of Migratory Species: From Global to Regional Scales : Final Report of the R&D-Projekt 808 05 081 |date=2004 |publisher=Federal Agency for Nature Conservation |isbn=9783784338453 |page=308}} meaning they migrate within freshwater river systems,{{cite report |last1=Gopalakrishnan |first1=Omkar |last2=Riede |first2=Klaus |title=Some observations on fish migration, with emphasis on tropical waters |date=2004 |publisher=Federal Agency for Nature Conservation |doi=10.13140/RG.2.1.5099.0969 |url=https://www.researchgate.net/publication/301867148 |access-date=12 October 2023}} and are endemic to rivers, lakes, and estuaries in Kerala and southern Karnataka in the Western Ghats of Peninsular India.{{cite journal |last1=Devi |first1=K.R. |last2=Indra |first2=T.J. |last3=Raghunathan |first3=M.B. |title=On a report of Tetradon (Monotretus) travancoricus, from south Kanara, Karnataka, India |journal=Journal of the Bombay Natural History Society |date=2000 |volume=97 |issue=3 |pages=441–443 |url=https://archive.org/details/biostor-151657/mode/2up |access-date=4 May 2022}} They can be found in waters with a pH of 7.5–8.3 and temperatures of {{convert|22–28|C|F|abbr=on}}. Inhabiting heavily vegetated waters with beds of gravel and rock or clay loam with silt and sand, the species is reported from 13 rivers in Kerala, lakes such as Vembanad,{{cite journal |last1=Devi |first1=K.R. |last2=Indra |first2=T.J. |last3=Emiliyamma |first3=K. J. |title=On the Fish Collections from Kerala, Deposited in Southern Regional Station, Zoological Survey of India by NRM Stockholm |journal=Records of Zoological Survey of India |date=1996 |volume=95 |pages=3–4 |url=http://faunaofindia.nic.in/PDFVolumes/records/095/03-04/0129-0146.pdf |access-date=4 May 2022}} the Nilambur harbours,{{cite journal |last1=Easa |first1=P.S. |last2=Basha |first2=C.C. |title=A Survey on the Habitat and Distribution of Stream Fishes in the Kerala part of Nilgiri Biosphere Reserve |journal=Kerala Forest Research Report |date=1995 |volume=104 |url=http://docs.kfri.res.in/KFRI-RR/KFRI-RR104.pdf |access-date=6 May 2022}} and Kallar Stream, part of the Neyyar Wildlife Sanctuary.{{cite journal |last1=Prasad |first1=G. |last2=Sabu |first2=K. |last3=Prathibhakumari |first3=P.V. |title=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 |journal=Journal on New Biological Reports |date=2012 |volume=1 |issue=2 |pages=42–46 |url=https://researchtrend.net/jnbr/jnbr/VOL%201(2)%202012/3%20Prasad%20et%20al,%202012.pdf |access-date=6 May 2022 |issn=2319-1104 |archive-date=13 July 2020 |archive-url=https://web.archive.org/web/20200713012131/https://www.researchtrend.net/jnbr/jnbr/VOL%201(2)%202012/3%20Prasad%20et%20al,%202012.pdf |url-status=dead }} They have been reported as rare in Bharathapuzha{{cite journal |last1=Bijukumar |first1=A. |last2=Philip |first2=Siby |last3=Ali |first3=Anvar |last4=Sushama |first4=S. |last5=Raghavan |first5=Rajeev |title=Fishes of River Bharathapuzha, Kerala, India: diversity, distribution, threats and conservation |journal=Journal of Threatened Taxa |date=26 November 2013 |volume=5 |issue=15 |pages=4979–4993 |doi=10.11609/JoTT.o3640.4979-93|doi-access=free }} and the Nilgiri Biosphere Reserve.{{cite journal |last1=Easa |first1=P.S. |last2=Shaji |first2=C.P. |title=Freshwater fish diversity in Kera a part of the Nilgiri Biosphere Reserve |journal=Current Science |date=1997 |volume=73 |issue=2 |pages=180–182|url=https://currentscience.ac.in/Volumes/73/02/0180.pdf}} The species was also found in inundated brickyards in Puthukkad,{{cite journal |last1=Biju, C.R. |first1=C.R. |last2=Thomas |first2=R.K. |last3=Ajithkumar |first3=C.R. |last4=George |first4=M.J. |title=Occurrence of Tetraodon travancoricus (Hora and Nair) in the Chalakudy, Periyar and Kechery rivers, Kerala |journal=Journal of the Bombay Natural History Society |date=1999 |volume=96 |issue=1 |page=161 |url=https://archive.org/details/biostor-151846/mode/1up |access-date=4 May 2022}} as well as ditches, ponds, irrigation channels, and artificial tanks or abandoned water bodies in paddy fields. Their presence in small, isolated water bodies is likely due to unintentional dispersal by waterfowl.{{cite journal |last1=Gopi |first1=K.C. |last2=Radhakrishnan |first2=C. |title=Waterbird-Mediated Chance-Dispersal of Fishes: A Natural Process of Affecting Range of Distribution and Biogeography of Fishes |journal=Records of the Zoological Survey of India |date=2007 |volume=108 |issue=1 |pages=19–31 |doi=10.26515/rzsi/v107/i1/2007/159160 |s2cid=201600208 |url=http://faunaofindia.nic.in/PDFVolumes/records/107/01/0019-0031.pdf |access-date=6 May 2022}}

Several researchers have considered the species endangered, though with no rationale provided.{{cite journal |last1=Dahanukar |first1=Neelesh |last2=Raut |first2=Rupesh |last3=Bhat |first3=Anuradha |title=Distribution, endemism and threat status of freshwater fishes in the Western Ghats of India |journal=Journal of Biogeography |date=22 December 2003 |volume=31 |pages=123–136 |doi=10.1046/j.0305-0270.2003.01016.x |s2cid=83574801 |url=http://wgbis.ces.iisc.ernet.in/biodiversity/sahyadri_enews/newsletter/issue53/bibliography/211-distribution-endemism-and-threat-status.pdf}}{{cite journal |last1=Thomas |first1=K. |last2=George |first2=M. |last3=Biju |first3=C. |title=Freshwater Fishes of Southern Kerala with Notes on the Distribution of Endemic and Endangered Species |journal=Journal of the Bombay Natural History Society |date=April 2002 |volume=99 |issue=1 |pages=47–53 |url=https://archive.org/details/biostor-152184/mode/2up |access-date=4 May 2022}}{{cite journal |last1=Raghavan |first1=R. |last2=Prasad |first2=G. |last3=Ali |first3=A.P.H. |last4=Pereira |first4=B. |title=Fish fauna of Chalakudy River, part of Western Ghats biodiversity hotspot, Kerala, India: patterns of distribution, threats and conservation needs |journal=Biodiversity and Conservation |date=2008 |volume=17 |issue=13 |pages=3119–3131|doi=10.1007/s10531-007-9293-0 |bibcode=2008BiCon..17.3119R |s2cid=7563806 }} 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. In 2010, some researchers estimated that the population would decline by 30–40% from 2005 to 2015, while others estimated it had already declined by the same amount between 2005 and 2010.{{cite journal |last1=Kurup |first1=B.M. |last2=Manojkumar |first2=T.G. |title=Central Marine Fisheries Research Institute |journal=Indian Journal of Fisheries |date=2010 |volume=57 |issue=1 |pages=81–85 |publisher=Central Marine Fisheries Research Institute |location=India |issn=0970-6011}}

Dwarf pufferfish are euryphagous carnivores in that they consume a wide variety of animals. Dwarf pufferfish favour insect larvae but will rely on crustaceans and annelids as alternate feed when the availability of preferable prey decreases. Their diet in the wild mainly consists of small animals such as water fleas, rotifers, copepods, and seed shrimp, and aquatic larvae such as those of Odonata, Hemiptera, mayflies, and flies, with some amounts of plant matter, largely diatoms and green algae. Sand and detritus, presumably ingested by mistake when feeding on small, bottom-dwelling animals, have also been found in their gut.

File:Carinotetraodon travancoricus shoaling.jpg

In captivity, dwarf pufferfish benefit from a varied diet and will eat small freshwater snails, shrimps, as well as foods like frozen mussel meat or other frozen shellfish. They will also readily eat live foods such as red and white mosquito larvae and other small animals they would predate in the wild.{{cite web |last1=Schäfer |first1=Frank |title=Carinotetraodon travancoricus |url=https://www.aquariumglaser.de/en/27-puffers/carinotetraodon-travancoricus-2/ |website=www.aquariumglaser.de |publisher=Aquarium Glaser GmbH |access-date=14 October 2023 |archive-url=https://web.archive.org/web/20231014181436/https://www.aquariumglaser.de/en/27-puffers/carinotetraodon-travancoricus-2/ |archive-date=14 October 2023 |date=20 November 2020}} 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.{{cite journal |last1=Anupama |first1=K.M. |last2=Harikrishnan |first2=M. |title=Improved survival of Malabar puffer fish, Carinotetraodon travancoricus (Hora and Nair, 1941) in planted aquaria |journal=International Journal of Environmental Sciences |date=2015 |volume=6 |issue=1 |pages=138–144 |doi=10.6088/ijes.6016 |doi-broken-date=1 November 2024 |url=https://www.indianjournals.com/ijor.aspx?target=ijor:ijes&volume=6&issue=1&article=016 |issn=0976-4402}}

Dwarf pufferfish are a slow-swimming, demersal (bottom-dwelling) species. Unlike many pufferfish species, which are primarily solitary and potentially aggressive or territorial between conspecifics (members of the same species),{{cite magazine |last1=Monks |first1=Neale |date=December 2007 |title=In Search of the Peaceful Puffer |url=https://www.tfhmagazine.com/articles/freshwater/in-search-of-the-peaceful-puffer |website=tfhmagazine.com |publisher=TFH Magazine |access-date=6 May 2022 |language=en}} dwarf pufferfish are found in large shoals, occasionally consisting of hundreds of individuals. They are found mainly during the summer months of January to May and rarely during the rainy season. Shoaling fish experience stress or weight loss when kept in solitude or in groups too small.{{cite journal |last1=Pagnussat |first1=Natália |last2=Piato |first2=Angelo L. |last3=Schaefer |first3=Isabel C. |last4=Blank |first4=Martina |last5=Tamborski |first5=Angélica R. |last6=Guerim |first6=Laura D. |last7=Bonan |first7=Carla D. |last8=Vianna |first8=Mônica R.M. |last9=Lara |first9=Diogo R. |title=One for All and All for One: The Importance of Shoaling on Behavioral and Stress Responses in Zebrafish |journal=Zebrafish |date=September 2013 |volume=10 |issue=3 |pages=338–342 |doi=10.1089/zeb.2013.0867|pmid=23802189 }}{{cite book |title=Coral fish stress out if separated from 'shoal-mates' |url=https://link.gale.com/apps/doc/A510692129/STND?u=wikipedia&sid=ebsco&xid=5f2b57d0 |access-date=13 May 2022 |publisher=Manila Bulletin Publishing Corp. |date=22 September 2016}}

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In 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.{{cite journal |last1=Anupama |first1=K.M. |last2=Hari Sankar |first2=H.S. |last3=Rithin Raj |first3=M. |last4=Harikrishnan |first4=M. |title=Reproductive Biology of Malabar Pufferfish Carinotetraodon travancoricus (Tetraodontidae) |journal=Journal of Ichthyology |date=July 2019 |volume=59 |issue=4 |pages=545–554 |doi=10.1134/S0032945219040027 |bibcode=2019JIch...59..545A |s2cid=201714471 |url=https://www.researchgate.net/publication/335583238 |access-date=6 May 2022 |issn=0032-9452}} Within the Pamba River, the minimum size at which half the population becomes sexually mature is approximately {{convert|1.83|cm|in|abbr=on}}. Environmental and dietary conditions may influence the maturation rate of individuals.

File:Carinotetraodon travancoricus by OpenCage.jpg

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. In the aquarium, dwarf pufferfish are often plant-spawners, laying eggs in plants, including java moss, or on the substrate hidden within plants. A female will scatter approximately 1–5 eggs, {{convert|1.43|mm|in|abbr=on}} 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. 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. Sneaking ejaculation by other males has also been observed. The pair may spawn multiple times in 1–4 day intervals.

Eggs hatch after five days at {{convert|27|C|F|abbr=on}}, with larvae and fry in captivity initially fed infusoria, Brachionus (a genus of rotifers), frozen bloodworms, and brine shrimp when they are a week old.{{Cite book |last=Ralph |first=Chris |year=2003 |title=Practical Fishkeeping: Pufferfish |pages=61 |publisher=Ringpress |isbn=1-86054-233-6}} There is little information on what the larvae eat in the wild. Hatched larvae are a mean of {{convert|3.15|mm|in|abbr=on}} total length, 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.

There is no information available on the lifespans of these fish in the wild, but aquarists report specimens live for approximately five years in captivity.

When first described in 1941, K. Nair noted that dwarf pufferfish were a favourite of children, who would catch and use the fish as playthings. They were regarded as "frog tadpoles" by local fishermen and otherwise given little consideration. They are of no interest to fisheries,{{cite book |last1=Talwar |first1=P. K. |last2=Jhingran |first2=A.G. |title=Inland fishes of India and adjacent countries |date=1991 |publisher=Oxford & IBH Pub. Co |location=New Delhi |isbn=9788120406391}} are not a food fish, and are only valued as ornamental fish in aquaria.{{cite book |last1=Ponniah |first1=A.G. |last2=Gopalakrishnan |first2=A. |title=Endemic fish diversity of Western Ghats |date=2000 |publisher=National Bureau of Fish Genetic Resources |location=Lucknow, India |isbn=81-901014-2-0 |pages=13–32 |url=https://eprints.cmfri.org.in/12661/1/Gopalakrishnan_2000_Endemic%20Diversity%20of%20the%20Western%20Ghats.pdf |access-date=5 May 2022}} Dwarf pufferfish have become popular as aquarium fish thanks to their attractive colours, small size, "puppy dog eyes", and relative ease of maintenance.{{cite journal |last1=Renjithkumar |first1=C.R. |last2=Roshni |first2=K. |last3=Ranjeet |first3=K. |title=Feeding ecology of the endemic freshwater puffer fish Carinotetradon travancoricus (Hora & Nair, 1941) in Western Ghats hotspot, India |journal=International Journal of Aquatic Biology |date=24 September 2020 |volume=8 |issue=5 |pages=300–310 |doi=10.22034/ijab.v8i5.922}} 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.{{cite book |last1=Anna Mercy |first1=T.V. |last2=Gopalakrishnan |first2=A. |last3=Kapoor |first3=D. |last4=Lakra |first4=W.S. |title=Ornamental fishes of the Western Ghats of India |date=2007 |publisher=National Bureau of Fish Genetic Resources |location=Lucknow |isbn=978-81-902951-8-5 |pages=227–228}}

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{{Reflist}}

{{Commons category|Carinotetraodon travancoricus}}

• [http://www.pufferfishenthusiastsworldwide.com/post/c-travancoricus Pufferfish Enthusiasts Worldwide Dwarf Pufferfish Care Sheet]

{{Taxonbar|from=Q175560}}

Category: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 that are or were threatened by the pet trade

Category:Species that are or were threatened by agricultural development

Category:Species that are or were threatened by urbanization

Category:Species that are or were threatened by damming

Category:Species that are or were threatened by deforestation