Which pufferfish are actually freshwater?

The pea puffer, the Congo puffers, the South American puffer, the red-eyed puffers, and the large Tetraodon species such as fahaka and mbu are true freshwater fish. Green spotted and figure-of-eight puffers are brackish and are frequently sold as freshwater, which is why they are also frequently short-lived.

What is the smallest pufferfish?

The pea puffer, at roughly 2-3cm. It is the only puffer that suits a nano tank, though it is still a predator and still needs snails.

Why do pufferfish teeth need wearing down?

A puffer's beak grows continuously. In the wild it is worn down by crushing shells; on soft aquarium food it keeps growing until the fish cannot feed. Snails and other hard-shelled food are part of the husbandry, not a treat.

Can pufferfish live with other fish?

Most are best alone. Puffers are fin-nippers and predators, and the larger species treat tank mates as food. A few of the small species can work in carefully chosen setups, but a species tank is the default rather than the fallback.

Pufferfish Types: Which Are Freshwater and How Big They Get

The freshwater problem

Pufferfish are sold as freshwater fish far more often than they are freshwater fish. The green spotted puffer is the usual example: it is stocked in freshwater tanks, lives for a while, and declines slowly in a way that is easy to blame on something else. It is a brackish species that moves toward full marine conditions as it matures.

So the first question about any puffer is not how big it gets. It is which water it actually needs.

Every puffer kept in aquaria, by water type

Freshwater

Species	Adult size	Min tank	Temperature	Temperament
The Pea Puffer: Carinotetraodon travancoricus	2-3 cm	—	24-28°C	Aggressive
The Spotted Congo Puffer: Tetraodon schoutedeni	3-4 inches (8-10 cm)	—	24-26°C	Peaceful / Semi-Aggressive
South American Puffer: Colomesus asellus	3-3.5 inches (8-9 cm)	—	24-28°C	Semi-Aggressive
The Red Eyed Puffer: Carinotetraodon lorteti	2.5 inches (6 cm)	—	24-28°C	Aggressive
Red Tailed Red Eyed Puffer: Carinotetraodon irrubesco	4-5 cm	—	24-28°C	Semi-Aggressive
Fang's Puffer: Pao cochinchinensis	3-4 inches (8-10 cm)	—	24-28°C	Aggressive
Bronze Puffer: Auriglobus modestus	10 cm (4 inches)	—	24-28°C	Aggressive
Pignose Puffer: Pao suvattii	5-6 inches (12-15 cm)	—	24-28°C	Predatory (Ambush)
Topaz Puffer: Dichotomyctere fluviatilis	6-7 inches (15-18 cm)	—	24-28°C	Aggressive
Potato Puffer: Tetraodon miurus	12-15 cm (5-6 inches)	—	24-28°C	Predatory (Ambush)
Humpback Puffer: Pao palembangensisPao palembangensis	20cm	150L	24-28°C	Aggressive
Hairy PufferPao baileyi	15cm	120L	24-28°C	Aggressive
Fahaka Puffer: Tetraodon lineatus	16-18 inches (40-45 cm)	—	24-28°C	Aggressive
The Mbu Puffer: Tetraodon mbu	60-75 cm (24-30 inches)	—	24-28°C	Aggressive / Interactive

Brackish / Marine

Species	Adult size	Min tank	Temperature	Temperament
Green Spotted PufferDichotomyctere nigroviridis	15cm	120L	24-28°C	Aggressive
Peacock Fugu Puffer: Takifugu rubripes	15 cm (6 inches)	—	22-27°C	Aggressive

Brackish

Species	Adult size	Min tank	Temperature	Temperament
The Figure of Eight Puffer: Dichotomyctere biocellatus	3 inches (8 cm)	—	22-26°C	Semi-Aggressive

Saltwater

Species	Adult size	Min tank	Temperature	Temperament
Valentini Puffer (Saddled Toby): Canthigaster valentini	3-4 inches	—	24-27°C	Semi-Aggressive
Jewel Pufferfish: Canthigaster solandriCanthigaster solandri	12cm	150L	24-27°C	Semi-Aggressive
Pacific Crowned PufferfishCanthigaster axiologus	10cm	115L	24-26°C	Semi-aggressive
Bennett's Sharpnose PufferfishCanthigaster bennetti	—	120L	24-26°C	Semi-aggressive
Porcupine PufferfishDiodon holocanthus	—	900L	24-26°C	Semi-aggressive
Whitespotted PufferfishArothron hispidus	—	1500L	24-26°C	Semi-aggressive

What the table does not show

Adult size is the second trap. The group runs from the pea puffer at 2-3cm to the mbu at 60-75cm. Those are not variations on a theme — the mbu is a fish that outgrows most domestic tanks and needs a volume measured in thousands of litres. Several of the mid-sized species sold as manageable reach 15-20cm and are territorial at that size.

The teeth are a husbandry requirement. A puffer's beak grows continuously and is worn down in the wild by crushing shells. On a diet of soft or prepared food it overgrows until the fish cannot eat, and correcting that means anaesthetising the fish and trimming it. The fix is preventive: snails, and other hard-shelled foods, routinely. If you keep puffers you will end up culturing snails, which is worth knowing before rather than after.

They are not community fish. Puffers nip fins, and the larger species eat what fits. Most are kept alone or in a species tank. The small ones are not exempt — a pea puffer is a predator scaled down, not a peaceful nano fish.

Skip the "puffing" question. A puffer inflating is a stress response, not a trick. Doing it out of water can force air into the fish and is genuinely harmful.

Choosing one

If you want a puffer in a small tank, the pea puffer is the only realistic option, and it still needs a snail supply and ideally a species tank. In the mid range the Congo puffers and the South American puffer are genuine freshwater species with real personality at a size a normal aquarium can accommodate. The large Tetraodon — fahaka, mbu — are specialist fish for people building around them.

If the fish you are drawn to is in the brackish or marine rows above, treat that as the starting constraint and plan the salinity before the tank.