Pufferfish Tanks and Dental Care: Freshwater, Brackish and Marine Puffers
Freshwater, brackish and marine pufferfish categories with tank sizes and salinity, continuously growing beaks and hard-shelled foods, trimming, aggression, and sensitivity to copper and dyes.
The family Tetraodontidae
Pufferfish form the family Tetraodontidae, which Wikipedia puts at roughly 193–206 species in 27–28 genera. The family name comes from the Greek for "four teeth": the jaws carry four beak-like tooth plates used to crack crustaceans and, in larger species, clams and mussels. When threatened, a puffer fills its highly elastic stomach with water or air until it is nearly spherical. Many species carry tetrodotoxin, concentrated in the ovaries and liver with smaller amounts in the intestine and skin. Most species are marine or brackish; about 35 live exclusively in fresh water, in South America (Colomesus), Africa (six Tetraodon species) and South and Southeast Asia (Auriglobus, Carinotetraodon, Dichotomyctere, Leiodon and Pao). In 2013 the Asian species formerly placed in Tetraodon were moved to Dichotomyctere, Leiodon and Pao (Wikipedia), so older literature uses other names for the same fish.
Three kinds of puffer tank
Freshwater
The dwarf or pea puffer, Carinotetraodon travancoricus, is the smallest commonly traded species: Seriously Fish gives 25 mm standard length, Wikipedia a maximum of 3.5 cm. It is endemic to Kerala and southern Karnataka in India and listed as Vulnerable on the IUCN Red List, mainly because of collection for the aquarium trade (Wikipedia; verify current status). Seriously Fish keeps a single fish in about 12.6 L (30 × 20 × 20 cm) and allows roughly 8–11 L per additional fish; PFK gives 25 L for a single fish and 15–20 L per specimen in groups; TFH allows 30 L (8 gallons) per fish to prevent fighting. All three stress dense planting and broken lines of sight. Water: 22–28 °C, pH 6.8–8.0 (Seriously Fish). The South American Colomesus asellus stays at 8–10 cm, is a genuine shoaling fish that TFH keeps in groups in soft, acidic water at 28–30 °C, and is a nervous, inconsistent fin-nipper rather than an outright predator.
Brackish
The genus Dichotomyctere occupies fresh and brackish water in South and Southeast Asia and reaches up to 17 cm (Wikipedia). The green spotted puffer (D. nigroviridis, often traded under the old name Tetraodon fluviatilis) grows to 12–15 cm and occasionally 20 cm; PFK keeps it at a specific gravity of at least 1.005 and TFH at 1.010 or higher, and both report that peaceful juveniles almost always become territorial, aggressive adults. The figure-eight puffer (D. ocellatus, formerly T. biocellatus) stays at 6–8 cm; PFK runs it at SG 1.002–1.005, TFH at around 1.005, and PFK suggests 75 L for the first fish plus 20–30 L for each additional one. The guide brackish-aquarium-guide explains how a brackish system is set up and measured.
Marine
Sharpnose or toby puffers (Canthigaster, 37 species) are the small marine option. TFH houses one in about 110 L (30 gallons) and a harem of one male with two or three females in about 380 L (100 gallons); they do not hunt fish but eat snails and sometimes corals, so reef compatibility is conditional. The large Arothron and Diodon puffers need very large systems: TFH quotes about 23 cm in the aquarium for A. nigropunctatus with a minimum of 75 gallons (about 280 L), 30 cm and 180 gallons (about 680 L) for A. hispidus, and 66 cm and over 300 gallons (about 1,100 L) for A. mappa, while porcupine puffers (Diodon) reach at least 61 cm. Their appetite produces a lot of waste, so TFH calls for efficient, oversized filtration.
Teeth: continuous growth and hard-shelled food
The fused tooth plates grow continuously. Seriously Fish states that the dwarf puffer must be fed small snails, shell on, regularly to keep the teeth in check; PFK extends the rule to all puffers, which should regularly receive whole, crunchy foods such as shrimp, snails and mussels; TFH observes that most prepared and frozen foods lack the "crunch" to wear down the fast-growing beak of Colomesus asellus, and that an overgrown beak makes eating difficult. PFK limits mussels and prawns to once or twice a week because of their thiaminase content and rejects goldfish and minnows as feeders. Susceptibility varies: PFK singles out Auriglobus and Chonerhinus as commonly affected by overgrown teeth, while TFH notes that Canthigaster teeth are far less prone to overgrowth than those of large puffers.
When trimming becomes necessary
If the beak has overgrown despite a hard diet, PFK describes the procedure used by keepers: the fish is placed in a container of aquarium water with a fish anaesthetic (2-phenoxyethanol at two to four drops per litre) for 30–60 seconds, lifted out, the tooth tips are trimmed with cuticle clippers, and the fish is held in a net in the aquarium until it recovers; the interval is typically three to twelve months. TFH mentions clove oil as an alternative anaesthetic.
Aggression and tankmates
TFH concludes that none of the commonly traded pufferfish can be considered a reliable community fish; their social behaviour is unpredictable even within a species. PFK likewise describes most Asian species as territorial and suited only to a tank of their own, with a few exceptions.
- Dwarf puffers can be kept in groups with at least two females per male; Seriously Fish warns that rival males have fought to the death, and recommends small suckermouth catfish such as Otocinclus as the only reliable companions, with mixed reports for shrimp.
- Figure-eight puffers get along with small gobies (PFK), and Colomesus asellus and the Mekong puffer (Pao suvattii) tolerate their own species in groups (PFK, TFH).
- TFH notes that a tank with a puffer is a tank without snails, which rules out ornamental snails as tankmates.
Water quality and medication sensitivity
Puffers are intolerant of poor water. TFH describes them as notoriously sensitive to high nitrate and low oxygen and recommends water changes of up to 50 percent weekly; PFK allows no measurable ammonia or nitrite, a filter turnover of six to ten tank volumes per hour, and weekly changes of 20–25 percent. Wild-caught individuals often arrive with parasites, and TFH quarantines new arrivals for at least three weeks.
Treatment options are narrower than for most fish. PFK states that puffers will not tolerate copper or formalin, nor organic dyes such as malachite green; TFH describes a marked intolerance of copper-based medications of the kind widely used against whitespot and fungus. Salt is species-dependent: PFK uses 2 g/L against whitespot and velvet and 5–10 g/L against slime disease in the Asian species, whereas TFH reports that the South American Colomesus does not do well with salt even as an ich treatment. Read the active ingredient of any product before dosing a puffer tank.