V. Sexing Carinotetraodon travancoricus, the Dwarf Puffer

Author: Amy J, AKA Myaj

Pufferfish are one of the most fascinating groups of aquatic creatures out there. Between their puffing abilities, unique swimming methods and intriguing personalities, they have quite a following. As more fish keepers strive to successfully keep and spawn puffers, they discover one of the largest challenges… accurately sexing the fish and convincing a group to live together in harmony, or at least tolerate each other. A very large portion of the puffer family does not display any externally visible gender differences and co-specifics are extremely aggressive to their tank mates, opposite sex or not. Therefore a successful pairing is extremely difficult, and attempts to keep pairs or groups often result in injured puffers and a distraught fish keeper. As a result, many puffer owners have resorted to keeping their fish as singletons.

Luckily for us, the Carinotetraodons are one of the few genus of puffers that can be accurately sexed, housed with co-specifics and successfully spawned by the home aquarist. The Dwarf Puffer, Carinotetraodon travancoricus, also known as the Pea Puffer, Pygmy Puffer and occasionally the Malabar Puffer, is a small, freshwater puffer found more and more often commercially. While Dwarf Puffers are considered to be somewhat less aggressive towards tank mates than other puffer species, they are still puffers and can inflict some impressive damage on any and all tank inhabitants. One of the key aspects to successfully keeping Dwarf Puffers, whether your goals are breeding or simply a stable display tank, is to stock the puffers at a 1:2 male to female ratio. In other words, have at least two females for every one male in the tank, and provide a minimum tank size of 3-5 gallons for each puffer.

This sounds easy enough, however, as any experienced fish-shopper has found out, most of the fish sold in commercial stores are juveniles. Dwarf Puffers do not display their adult sexual characteristics until they are nearly full grown, usually between .5” to 1” in body length. When they are smaller, it is more difficult to accurately sex the puffers as both sexes resemble females in general appearance. As an added challenge, stressed, sick or frightened puffers will often dull their colors to a point where gender features are indistinguishable. To the educated eye, however, there are many differences and accurate sexing is certainly possible. Keep in mind, not all characteristics may be visible in all specimens, but the following are the most commonly seen sexual differences.

Male Dwarf Puffers are generally the easier gender to identify. They have several distinct features that females do not. One of the first characteristic features to appear on a maturing male Dwarf Puffer is yellow body coloring, especially on the belly and tail. Males also have “wrinkles” around their eyes, markings that almost look like iridescent cracks in the skin surrounding the eye socket. A dark belly stripe, running from just under the chin to the anus, is another easily visible male characteristic. The male body color is often darker shades of green on the top part of the body, and the spotted markings will tend to blend into lines resembling blotchy stripes running laterally down the sides and into the tail of the puffer as it matures, instead of the random, isolated spots of a juvenile. Males will often “display” to the females and other males, raising dorsal (topline) and ventral (belly line) crests and darkening their body colors to an olive green.

Male specimen showing eye “wrinkles”, dark green/yellow body color and striped body markings Photo of male specimen showing yellow belly color and dark belly stripe

Female Dwarf Puffers are less streamlined, and have rounder bellies and slightly larger bodies than males. Their markings will differ with each individual fish, but often remain similar to juvenile colors and markings. The body spots are generally isolated round or irregular, in no distinct pattern. The lower body is generally white or light colored, with no belly line running down the center. Females are often less shy and more active than males, spending most of their time on the search for anything edible.

Female specimen

Using these identification guidelines, it should be relatively easy to set up a properly stocked and acceptably peaceful dwarf puffer habitat that will keep you entertained, amused and interested for years to come.