(Hora & K. K. Nair, 1941)
The dwarf pufferfish (Carinotetraodon travancoricus), also known as the Malabar pufferfish (leading to easy confusion with the related C. imitator), pea pufferfish or pygmy pufferfish, is a small, freshwater pufferfish endemic to the River Pamba in Kerala, Southwest India. Maximum size is 22 mm (less than one inch), making it one of the smallest pufferfish in the world. Although closely related to marine pufferfish, they are not found in brackish or salt water, and reports to the contrary may be based on misidentification.
Sexing of juveniles is impossible because these fish "choose" their sex as they mature. Once one puffer begins becoming a male he excretes hormones to prevent the other puffers from becoming male. However, if two fish start to mature into males at the same time one will become the dominant male.There is also a dorsal crest, but it lacks special colouration when not erected. Both crests are displayed during courtship while the male circles the female. They also will have more yellow colouration.
Both sexes are primarily yellow with dark green to black iridescent patches on the flanks and dorsal surface, but as with other members of the genus, sexual dimorphism is apparent in mature fish, with males being more brightly coloured than females. Males can also have a dark stripe down the center of their pale belly and iridescent "eye wrinkle" patterns that females do not have. Females are more rounded, tend to be a bit larger than males, and may or may not show more smallish spots between their larger dark markings.
Often dwarf pufferfish are plant-spawners, laying eggs in plants, including java moss in aquariums. Eggs have been seen to hatch after five days at 27 °C (81 °F), with fry initially feeding on infusoria, brine shrimp when they're a week old, and finally regular-sized food when possible. Dwarf pufferfish have also been known to scatter their eggs on the substrate hidden within vegetation. The eggs are fertilized externally. They do not guard their eggs or fry. After the eggs hatch, take out the fry; it is not recommended that you keep the adults and the fry together. A small tank of about ten gallons is acceptable.
Dwarf pufferfish are not used as food but are traded as aquarium fish. It has been classified as "vulnerable" on the IUCN Red List due to changes in habitat and overharvesting for the aquarium trade. 
The diet of dwarf pufferfish in the wild has not been reported, but other members of the genus feed on zooplankton and various benthic crustaceans and molluscs. Food items of specimens maintained in aquaria appears to be similar. In fact, the dwarf puffer is one of the few aquarium fish to regularly eat small live snails and can be useful in controlling snail populations (larger snails do not interest them).
Dwarf pufferfish in aquaria
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Dwarf pufferfish have become quite popular as aquarium fish thanks to their attractive colours, small size, and relative ease of maintenance. Like all pufferfish, they can be aggressive, especially towards creatures smaller than themselves, and it is commonly recommended to keep them in a dedicated "species only" tank. A female to male ratio of 3 to 1 is sometimes recommended to reduce aggression in captive fish.
- Dahanukar, N. (2010). "Carinotetraodon travancoricus". IUCN Red List of Threatened Species. Version 2011.1. International Union for Conservation of Nature. Retrieved 28 June 2011.
- Klaus Ebert (2001). The Puffers of Fresh and Brackish Water. Aqualog. pp. 19, 46–49. ISBN 3-931702-60-X.
- Schäfer F. Brackish Water Fishes, p 34. Aqualog 2005, ISBN 3-936027-82-X
- Ralph, Chris (2003). Practical Fishkeeping: Pufferfish, p. 61. ISBN 1-86054-233-6
- Froese, R. and D. Pauly. Editors. "Reproduction Summary: Carinotetraodon travancoricus". FishBase. Retrieved 2007-03-07.
- Wenzel, R. (2004). Carinotetraodon travancoricus. Die Aquarien- und Terrarienzeitschrift 1/2004:36-37
- Froese, R. and D. Pauly. Editors. "Food Items Reported for Carinotetraodon lorteti". FishBase. Retrieved 2007-03-07.
- Froese, Rainer and Pauly, Daniel, eds. (2007). "Carinotetraodon travancoricus" in FishBase. March 2007 version.
- Care information for Dwarf Puffers kept in the home Aquarium