Taxonomy & naming
Carinotetraodon salivator was described by Lim and Kottelat in 2001. The Catalog of Fishes (Eschmeyer, CAS) recognises the valid combination as Carinotetraodon salivator Lim & Kottelat, 2001. The genus Carinotetraodon — the dwarf puffers of South and Southeast Asia — is distinct from the African genus Tetraodon, to which many Asian pufferfish were formerly assigned before the group was extensively revised. Tetraodon is now restricted to African species; the Asian dwarf puffers sit in Carinotetraodon, the Mekong river puffers in Pao, the brackish Asian species in Dichotomyctere, and the South American species in Colomesus.
Within Carinotetraodon, the species is part of a Sundaic radiation that includes C. lorteti, C. irrubesco and C. borneensis on Borneo and Sumatra, distinguished from the Indian species C. travancoricus and C. imitator of the Western Ghats. C. salivator is most likely to be confused with C. lorteti in the field, and careful comparison of colouration and geographic origin is needed for correct identification. GBIF records the species page under taxon key 2407800.
Morphology
C. salivator is a small, rounded pufferfish reaching 1.5–2 in standard length. Like all tetraodontids, it lacks true scales, carrying instead a covering of small prickles over the body that erect when the fish inflates. The body is deep and laterally compressed compared with most fish, tapering sharply toward the caudal peduncle. The distinctive four fused teeth — two upper and two lower — form a parrot-like beak that is clearly visible and never stops growing, requiring hard-shelled food throughout the fish's life.
The species name alludes to a pale blotch on the lower lip. Body colouration is brownish-green to olive dorsally with a pattern of darker stripes or blotches, and a pale to whitish ventral surface; the eye is typically vivid red, giving rise to the common name striped redeye puffer. Males show more intense colouration and develop a prominent mid-ventral keel and dorsal ridge during courtship, characters shared with close relatives in the genus.
Habitat
The species is known from the Lupar, Sarawak and Rajang River systems of Sarawak, Malaysian Borneo — three river basins that define its entire documented range. Collection data from the type locality describe fast-flowing streams approximately 15 metres wide with clayey, undercut banks, a substrate of soft silt and sand with abundant leaf litter and submerged logs, and riffle-like rocky stretches. Peat swamp forest streams with tannin-stained, softly acidic water are characteristic habitat.
The water parameters recorded across its range are soft to moderately hard, slightly acidic to near-neutral: temperature 68–82 °F, pH 5.0–7.5, hardness broadly 18–215 ppm. This reflects the dark, tea-coloured, mineral-poor waters of Bornean peat swamp and forest streams, quite different from the harder, more alkaline waters of many aquarium fish. C. salivator is strictly freshwater; there is no evidence of any tolerance for brackish conditions.
Feeding
C. salivator is a molluscivore and invertebrate predator, as are its congeners. In its natural streams it targets snails, small crustaceans, and other hard-shelled invertebrates, using its powerful beak to crack shells. The beak is not merely a feeding tool but a structural necessity: the four teeth grow continuously throughout life, and without regular contact with hard-shelled food the beak overgrows into a deformity that prevents feeding and requires veterinary trimming.
In the aquarium, the staple diet should be live or frozen snails (ramshorn, bladder snails), small shrimp and other crustaceans, supplemented with earthworms and bloodworms. Soft foods such as flake are insufficient alone to maintain dental wear. A varied diet of suitably sized shelled prey keeps the beak in good condition and maintains the fish's health and coloration.
Mating
In Carinotetraodon, males are strongly territorial and display to females using vivid colouration and the inflatable belly-keel and dorsal ridge that develop during the breeding season. A ready male pursues a ripe female with persistent chasing, displaying laterally to show off the ventral keel, and may court her over an extended period before spawning is achieved.
The pair bond is temporary and centred on the spawning act. As in close relatives such as C. lorteti, the male takes up a guarding role once eggs are deposited, remaining near the clutch and defending it against disturbance. Females are typically sought out by a dominant male in a territory; subordinate males or excess females can be harassed persistently in confined spaces, which has significant implications for aquarium management.
Breeding
Breeding in C. salivator follows the substrate spawning pattern documented for the genus: the female deposits adhesive eggs low among fine-leaved plants, moss or other submerged structure, and the male then guards the clutch until hatching. Eggs are reported to hatch in approximately three days at tropical temperatures, with fry becoming free-swimming shortly afterward. Early fry require infusoria or similarly fine live foods, graduating to newly hatched brine shrimp as they grow.
The male's guarding behaviour is the defining feature of breeding in this genus and distinguishes Carinotetraodon from the egg-scattering, non-guarding pattern of many small tropical fish. For the aquarist attempting to breed the species, a densely planted spawning setup with a single confirmed pair is advisable, removing the female after spawning to prevent the guarding male from harassing her and to allow undisturbed egg development.
In the aquarium
C. salivator is an advanced-level species suited to experienced keepers who understand pufferfish-specific requirements. It should be kept alone or in a species-only setup: like most puffers it is an aggressive fin-nipper and will attack any tankmates, including other puffers outside a managed breeding pair. Even within the species, males are territorial and should not be kept together in small volumes. A single specimen or a carefully monitored male-female pair is the practical approach.
The minimum aquarium should be well-planted with fine-leaved vegetation and provide soft, acidic, well-oxygenated water matching the peat swamp conditions of Borneo: temperature 72–79 °F, pH 6.6–7.5, soft to moderately hard. The species is strictly freshwater; brackish conditions are harmful. Puffers produce heavy waste and require robust filtration with regular large water changes. Because puffers lack true scales and gill covers they are sensitive to medication — copper-based treatments must never be used, and all chemical doses should be reduced and administered with caution.
The fish should never be deliberately stressed into inflating — although they can inflate readily with water when threatened, repeated inflation is physically exhausting and stressful. They must never be lifted into the air, as inflation in air can be fatal. The skin and organs contain tetrodotoxin; while handling risk in aquarium keeping is low, the toxin is highly dangerous if ingested and hands should be washed after any contact with the fish or its tank water. Given the correct conditions and a diet of varied shelled invertebrates, C. salivator is a rewarding and characterful fish with a long lifespan.
Conservation
Carinotetraodon salivator is assessed as Near Threatened (NT) on the IUCN Red List, assessed December 2019 under criteria B1b(iii). The assessment reflects the species' extremely restricted range — known only from three river systems in Sarawak — and the ongoing degradation of lowland peat swamp forest across Borneo through logging, plantation conversion (particularly oil palm), drainage of peat swamps, and associated pollution of waterways. These pressures directly reduce and fragment the soft-bottomed, shaded stream habitat on which the species depends.
The species does not benefit from the broad distribution that buffers more widespread freshwater fish against localised decline, and its apparent restriction to three basins means that habitat loss in any of those systems directly reduces global population size. Collection for the aquarium trade adds a further pressure on an already limited wild population. Captive breeding in the hobby, where achievable, reduces demand on wild-caught individuals and is encouraged. Continued survey work in Sarawak's rivers is needed to clarify the species' true distributional limits and population trends before a more comprehensive assessment is possible.