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{{Use dmy dates|date=September 2020}}
{{Taxobox
| name               = Dwarf pufferfish
| image              = アベニーパファー.jpg
| image_alt          = An adult dwarf pufferfish against a white background. We can see the fish from its side. It is looking slightly upward.
| image_caption      = An adult dwarf pufferfish
| regnum             = [[Animalia]]
| divisio            = [[Chordata]]
| classis            = [[Actinopterygii]]
| ordo               = [[Tetraodontiformes]]
| familia            = [[Tetraodontidae]]
| genus              = ''[[Carinotetraodon]]''
| species            = '''''C. travancoricus'''''
| binomial           = '''''Carinotetraodon travancoricus'''''
| binomial_authority = ([[Sunder Lal Hora|Hora]] & K.K. Nair, 1941)<ref name="Hora 1941" />
| synonyms           =
  {{Species list
  |''Tetraodon travancoricus''|Hora & K.K. Nair, 1941
  |''Monotretus travancoricus''|Hora & K.K. Nair, 1941
  }}
| synonyms_ref = <ref name="iucn status 19 November 2021" /><ref name="Hora 1941" />
}}

'''Dwarf pufferfish''' (''Carinotetraodon travancoricus''), also called '''Malabar pufferfish''', '''pygmy pufferfish''', or '''pea pufferfish''', are small [[freshwater]] [[pufferfish]]. They [[Endemism|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 {{convert|3.5|cm|in|abbr=off}}. 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 [[Vegetation|plant life]]. They [[Predation|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==
The dwarf pufferfish was first described as ''Tetraodon (Monotretus) travancoricus'' in 1941 by [[Sunder Lal Hora|S.L. Hora]] and K.K. Nair, with the [[type locality (biology)|type locality]] given as "[[Pamba River]], Central [[Travancore]]". ''Carinotetraodon'' was considered a [[Synonym (biology)|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 [[Maurice Kottelat|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 language|Greek]] words "''tetra''" (four) and "''odous''" (teeth).<ref name=fishbase>{{FishBase|genus= Carinotetraodon |species= travancoricus |year=2017|month=January}}</ref> The justification for moving to ''Carinotetraodon'' was based largely on [[osteological]] evidence and not on the presence of skin [[keel]]s, which other members of the genus have, but which had not been confirmed in dwarf pufferfish until one year later in aquarium literature.<ref name="Britz 2012" /> Specifically, dwarf pufferfish possess [[vertebral]] [[Modifications (genetics)|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.<ref name="Britz 1999">{{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_Carinotetraodon_imitator_a_new_freshwater_pufferfish_from_India_Teleostei_Tetraodontiformes |access-date=19 May 2022 |publisher=Wildlife Heritage Trust of Sri Lanka |location=Sri Lanka |issn=1022-0828}}</ref>

''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'':<ref name="Sathyajith 2019">{{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}}</ref>
[[File:Tetraodon nigroviridis 1.jpg|thumb|The closely related ''Dichotomyctere nigroviridis'']]

{{clade
|label1=Tetraodontidae
|1={{clade
   |label1=
   |1={{clade
      |label1=
      |1={{clade
         |1=''[[Auriglobus modestus]]''
         |label2=
         |2={{clade
            |1=''[[Leiodon cutcutia]]''{{efn|name=fresh}}
            |label2=
            |2={{clade
               |label1=
               |1={{clade
                  |1=''[[Carinotetraodon salivator]]''{{efn|name=fresh}}
                  |2=''[[Carinotetraodon lorteti]]''{{efn|name=fresh}}
                  }}
               |label2=
               |2={{clade
                  |1=[[Pao palembangensis]]''{{efn|name=fresh}}
                  |2=''[[Pao cochinchinensis]]''{{efn|name=fresh}}
                  }}
               }}
            }}
         }}
      |label2=
      |2={{clade
         |label1=
         |1={{clade
            |label1=
            |1={{clade
               |1='''''Carinotetraodon travancoricus'''''{{efn|name=fresh}}
               }}
            |label2=
            |2={{clade
               |label1=
               |1={{clade
                  |1=''[[Dichotomyctere nigroviridis]]''
                  |2=''[[Dichotomyctere ocellatus]]''
                  }}
               }}
            }}
         |label2=
         |2={{clade
            |label1=
            |1={{clade
               |1=''[[Pelagocephalus marki]]''
               }}
            |label2=
            |2={{clade
               |label1=
               |1={{clade
                  |1=''[[Canthigaster coronata]]''
                  |label2=
                  |2={{clade
                     |1=''[[Canthigaster rivulata]]''
                     |label2=
                     |2={{clade
                        |1=''[[Canthigaster jactator]]''
                        |2=''[[Canthigaster valentini]]''
                        }}
                     }}
                  }}
               }}
            }}
         }}
      |label3=
      |3={{clade
         |label1=
         |1={{clade
            |label1=
            |1={{clade
               |1=''[[Chelonodon pleurospilus]]''
               }}
            |label2=
            |2={{clade
               |1=''[[Chelonodon patoca]]''
               }}
            }}
         |label2=
         |2={{clade
            |label1=
            |1={{clade
               |1=''[[Tetraodon miurus]]''{{efn|name=fresh}}
               }}
            |label2=
            |2={{clade
               |1=''[[Tetraodon mbu]]''{{efn|name=fresh}}
               }}
            }}
         }}
      }}
   }}
}}

==Description==
[[File:Carinotetraodon travancoricus by Parazelsus (cropped).jpg|thumb|left|Dwarf pufferfish have dark, iridescent patches on their flanks and dorsal surfaces|alt=A dwarf pufferfish in an aquarium, displaying its iridescent patches.]]
The maximum documented size is {{convert|3.5|cm|in|abbr=on}} [[Fish measurement|total length]] (TL),<ref name="Jhingran 1991" /> with individuals typically reaching less than {{convert|2.5|cm|in|abbr=on}} TL,<ref name=fishbase>{{FishBase|genus= Carinotetraodon |species= travancoricus |year=2017|month=January}}</ref> making dwarf pufferfish one of the smallest pufferfish in the world.<ref name="Ebert">{{cite book |author=Klaus Ebert |year=2001 |title=The Puffers of Fresh and Brackish Water |publisher=Aqualog |isbn=3-931702-60-X |pages=19, 46–49}}</ref> Both sexes are primarily greenish-yellow, with dark green to brown-black [[iridescent]] patches on the [[Flank (anatomy)|flanks]] and [[Dorsal (anatomy)|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 fin|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.<ref name="Hora 1941" /><ref name="Anna Mercy 1999" /> As with other members of the genus, sexual dimorphism is apparent in mature fish, with males being more brightly coloured than females<ref name="Ebert"/> and having a yellow [[ventral]] surface.<ref name="Hellweg 2007" /> 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.<ref name="Hellweg 2007" />
{{clear}}

===Natural defenses===
All pufferfish can inflate their bodies by quickly ingesting large amounts of water (or air when necessary) into their highly elastic [[stomachs]].<ref name="Nat Geo Pufferfish" /> Like many other pufferfish, in the absence of scales, dwarf pufferfish also have skin [[Spine (zoology)|spines]] on most of their body.<ref name="Britz 1999" /><ref name="Britz 2012">{{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: An international journal for field-orientated ichthyology |date=October 2012 |volume=23 |issue=2 |pages=105-109 |url=https://www.researchgate.net/publication/256202390_First_record_from_the_wild_of_Carinotetraodon_imitator_in_Peninsular_India_Teleostei_Tetraodontiformes_Tetraodontidae |access-date=1 May 2022 |issn=0936-9902}}</ref><ref>{{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 |url=https://reader.elsevier.com/reader/sd/pii/S2589004219301853?token=3427A279E4C3484DD6098CF36683B63E1233E8815F574F8F91BAF43B04643E85E146D371B0AC60A93C534967BC50B367&originRegion=us-east-1&originCreation=20220601032423 |access-date=31 May 2022}}</ref> These spines become erect when the fish is inflated. These characteristics are [[anti-predator adaptation]]s that make the fish difficult to swallow or bite. Biologists believe these adaptations evolved because of the slow swimming speeds of pufferfish.<ref name="Nat Geo Pufferfish">{{cite web |title=Pufferfish {{!}} National Geographic |url=https://www.nationalgeographic.com/animals/fish/facts/pufferfish |website=www.nationalgeograph.orc |publisher=[[National Geographic]] |access-date=28 May 2022 |language=en |date=12 March 2010}}</ref><ref name="Seattle Aquarium 2013">{{cite web |title=Why do pufferfish "puff up"? {{!}} Seattle Aquarium |url=https://www.seattleaquarium.org/blog/why-do-pufferfish-puff#:~:text=Pufferfish%20will%20%E2%80%9Cpuff%20up%E2%80%9D%20as,very%20appetizing%20to%20a%20predator. |website=www.seattleaquarium.org |publisher=[[Seattle Aquarium]] |access-date=29 May 2022 |date=11 January 2013}}</ref> 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.<ref name="Seattle Aquarium 2013" />

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.<ref name="Hellweg 2007">{{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 |website=www.tfhmagazine.com |publisher=[[Tropical Fish Hobbyist|TFH Magazine]] |access-date=5 May 2022 |language=en}}</ref>

===Resemblance to ''Carinotetraodon imitator''===
''[[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 (biology)|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''.<ref name="Britz 1999" />

==Distribution and habitat==
Although closely related to marine pufferfish, they are not found in salt water, and reports to the contrary are based on misidentification.<ref>Schäfer F. Brackish Water Fishes, p 34. Aqualog 2005, {{ISBN|3-936027-82-X}}</ref> Dwarf pufferfish are one of only 27 known species of Tetraodontidae known to be adapted to freshwater.<ref name="Doi 2015">{{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}}</ref> They are a migratory, or [[potamodromous]], species<ref name="fishbase 1">{{FishBase species|genus=Carinotetraodon|species=travancoricusus|year=2021|month=September}}</ref><ref name="fishbase 2">{{cite web |title=Carinotetraodon travancoricus (Hora & Nair, 1941) Malabar pufferfish |url=https://www.fishbase.de/summary/Carinotetraodon-travancoricus.html |access-date=5 May 2022 |website=www.fishbase.de |publisher=[[FishBase]]}}</ref> endemic to rivers, lakes, and [[estuaries]]<ref name="Sabu 2012" /> in Kerala and southern Karnataka in the [[Western Ghats]] of [[Peninsular India]].<ref name="iucn status 19 November 2021" /><ref name="Easa 1995" /><ref name="Devi 2000">{{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}}</ref> They can be found in waters with a [[pH]] ranging from 7.5–8.3 and temperatures ranging from {{convert|22–28|C|F|abbr=on}}.<ref name="fishbase 2" /> Inhabiting heavily [[vegetated]] waters with beds of gravel and rock or [[clay loam]] with silt and sand,<ref name="Sabu 2012" /> the species is reported from 13 rivers in Kerala,<ref name="Anupama 2015" /> including Pamba River,<ref name="Hora 1941">{{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}}</ref> [[Chalakudy River]],<ref name="Raghavan 2008" /> [[Periyar (river)|Periyar]], [[Kechery]],<ref name="Biju 1999">{{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}}</ref> [[Muvattupuzha]],<ref name="Beevi 2009">{{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}}</ref> [[Vembanad]], [[Meenachil River]], [[Cherthala]],<ref name="Devi 1996">{{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}}</ref> [[Nilambur]] harbours,<ref name="Easa 1995">{{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}}</ref> and [[Kallar Stream]], part of the [[Neyyar Wildlife Sanctuary]].<ref name="Sabu 2012">{{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}}</ref> They have been reported as rare in [[Bharathapuzha]]<ref name="Bijukumar 2013">{{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}}</ref> and the [[Nilgiri Biosphere Reserve]].<ref name="Easa 1997">{{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}}</ref> The species was also found in [[inundated]] brickyards in [[Puthukkad]],<ref name="Biju 1999" /> as well as ditches, ponds, [[irrigation]] [[Canal|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 [[Piscivore|piscivorous]] birds inadvertently dispersing individuals.<ref name="Gopi 2007">{{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 |url=http://faunaofindia.nic.in/PDFVolumes/records/107/01/0019-0031.pdf |access-date=6 May 2022}}</ref>

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 [[Predation|predate]] the dwarf pufferfish, but did not identify the particular bird species.<ref name="Gopi 2007" />

===Conservation status===
Several researchers have considered the species [[Endangered species|endangered]], though with no rationale provided.<ref name="Dahanukar 2003">{{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 |url=http://wgbis.ces.iisc.ernet.in/biodiversity/sahyadri_enews/newsletter/issue53/bibliography/211-distribution-endemism-and-threat-status.pdf}}</ref><ref>{{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}}</ref><ref name="Raghavan 2008">{{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}}</ref> The dwarf pufferfish is officially classified as [[Vulnerable species|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.<ref name="iucn status 19 November 2021" /><ref name="Anupama 2015" /> In 2010, some researchers estimated that the population would decline by 30–40% from 2005 to 2015,<ref name="iucn status 19 November 2021" /><ref name="Dahanukar 2003" /> while others estimated it had already declined by the same amount between 2005 and 2010.<ref>{{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}}</ref>

==Diet and behaviour==
Dwarf pufferfish are [[Wiktionary:euryphagous|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.<ref name="Renjithkumar 2020" /> Their diet in the wild mainly consists of small animals such as [[Cladocera]], [[rotifer]]s, [[copepod]]s, 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]].<ref name="Sabu 2012" /><ref name="Renjithkumar 2020" /> Sand and [[detritus]], presumably ingested by mistake when feeding on small, bottom-dwelling animals, have also been found in the gut of dwarf pufferfish.<ref name="Sabu 2012" /><ref name="Renjithkumar 2020" />

[[File:Carinotetraodon_travancoricus_shoaling.jpg|left|thumb|Dwarf pufferfish shoaling in the wild, seen from above|alt=Several wild dwarf pufferfish are viewed from above in yellowish water]] 
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 [[Chironomidae|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]].<ref>{{cite web|url=http://filaman.ifm-geomar.de/TrophicEco/FoodItemsList.cfm?vstockcode=19922&genus=Carinotetraodon&species=lorteti&CFID=2205913&CFTOKEN=31807211|title=Food Items Reported for Carinotetraodon lorteti |editor=Froese, R. |editor2=D. Pauly|publisher=FishBase|access-date=7 March 2007}}</ref> Food items of specimens maintained in aquaria appear to be similar.<ref name="Ebert"/> 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.<ref name="Anupama 2015">{{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 |url=https://www.researchgate.net/publication/294085437_Improved_survival_of_Malabar_puffer_fish_Carinotetraodon_travancoricus_Hora_and_Nair_1941_in_planted_aquaria |access-date=5 May 2022 |issn=0976-4402}}</ref>

Dwarf pufferfish are a slow-swimming,<ref name="Gopi 2007" /> [[demersal fish|demersal]], or bottom-dwelling, species.<ref name="fishbase 1" /><ref name="fishbase 2" /> Unlike many pufferfish species, which are primarily solitary and potentially aggressive or territorial between [[Biological specificity#Conspecific|conspecifics]] (members of the same species),<ref>{{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=[[Tropical Fish Hobbyist|TFH Magazine]] |access-date=6 May 2022 |language=en}}</ref> dwarf pufferfish are found in large [[Shoaling and schooling|shoals]], occasionally consisting of hundreds of individuals.<ref name="Biju 1999" /> They are found mainly during the summer months (January to May) and rarely during the rainy season.<ref name="Biju 1999" /> Shoaling fish are known to experience [[Stress (biology)|stress]] or weight loss when kept in solitude or in groups too small.<ref>{{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}}</ref><ref>{{cite news |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 |work=Manila Bulletin |publisher=Manila Bulletin Publishing Corp. |date=22 September 2016}}</ref>
{{clear}}

==Reproduction==
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 [[Monsoon of South Asia|South-West monsoon]] period.<ref name="Anupama 2019">{{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 |url=https://www.researchgate.net/publication/335583238_Reproductive_Biology_of_Malabar_Pufferfish_Carinotetraodon_travancoricus_Tetraodontidae |access-date=6 May 2022 |issn=0032-9452}}</ref> 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.<ref name="Anupama 2019" /> 

[[File:Carinotetraodon travancoricus by OpenCage.jpg|thumb|A juvenile dwarf pufferfish in an aquarium|alt=Left-side view of a juvenile dwarf pufferfish against a blank background.]]
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.<ref name="Doi 2015" /> In the aquarium, dwarf pufferfish are often plant-spawners, laying eggs in plants, including [[java moss]], or on the substrate hidden within plants.<ref name="Chris 2003" /> 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.<ref name="Doi 2015" /> 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.<ref name="Doi 2015" /> Sneaking ejaculation by other males has also been observed.<ref name="Doi 2015" /> The pair may spawn multiple times in 1–4 day intervals.<ref name="Doi 2015" />

Eggs hatch after five days at {{convert|27|C|F|abbr=on}}, with larvae and [[Fry (biology)|fry]] initially fed [[infusoria]], ''[[Brachionus]]'', frozen bloodworms, and brine shrimp when they are a week old.<ref name="Chris 2003">Ralph, Chris (2003). Practical Fishkeeping: Pufferfish, p. 61. {{ISBN|1-86054-233-6}}</ref><ref name="Doi 2015" /> There is little information on what the larvae eat in the wild.<ref name="Ebert" /> Hatched larvae are a mean of {{convert|3.15|mm|in|abbr=on}} 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.<ref name="Doi 2015" />

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.<ref name="Hellweg 2007" />

==Association with humans==
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.<ref name="Hora 1941" /> They were regarded as "frog tadpoles" by local fishermen<ref name="Biju 1999" /> and otherwise given little consideration. They are of no interest to [[fisheries]],<ref name="Jhingran 1991">{{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}}</ref> are not a [[food fish]], and are only valued as [[ornamental fish]] in aquaria.<ref>{{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}}</ref><ref name="iucn status 19 November 2021" /> Dwarf pufferfish have become popular as aquarium fish thanks to their attractive colours, small size, "[[Wiktionary:puppy dog eyes|puppy dog eyes]]", and relative ease of maintenance.<ref name="Ebert" /><ref name=Wenzel>Wenzel, R. (2004). ''Carinotetraodon travancoricus''. Die Aquarien- und Terrarienzeitschrift 1/2004:36-37</ref><ref name="Renjithkumar 2020">{{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}}</ref> 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.<ref name="Anna Mercy 1999">{{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=81-902951-8-7 |pages=227-228}}</ref>
{{clear}}

==Notes==
{{Notelist |refs=
{{efn|name=fresh|Freshwater species}}
}}

==References==
{{Reflist|refs=
<ref name="iucn status 19 November 2021">{{cite iucn |author=Dahanukar, N. |date=2011 |title=''Carinotetraodon travancoricus'' |volume=2011 |page=e.T166591A174788004 |doi=10.2305/IUCN.UK.2011-1.RLTS.T166591A174788004.en |access-date=4 May 2022}}</ref>

}}

==External links==
{{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 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]]