This care sheet is written with the aim of providing the optimal care for this species of fish.
Pufferfish Enthusiasts Worldwide endeavours to inspire and promote the highest standards of care - not basic or minimum care - using the best evidence available at the time.
The turgidus is a species of freshwater pufferfish belonging to the Pao genus.
The P.turgidus previously belonged to the Monotrete and then the Tetraodon genera, until being reassigned in 2013 to Pao.
Common names for this species include Cambodian Mekong Puffer, Spotted Target Puffer, Brown Puffer, Asian Spotted Puffer and Chameleon Puffer.
The specific name comes from the Latin word turgidus, meaning "swollen, inflated".
In the wild
The P.turgidus has a distributional range throughout the Mekong river basin and many of its tributaries. It can be found in Xishuangbanna (China), Laos, Thailand, Vietnam and Cambodia.
It lurks within the dense submerged vegetation of its suitable habitats, ready to launch a surprise attack on any prey items that swim within striking distance.
It feeds on smaller species of fish, freshwater crustaceans and benthic animals such as worms.
This species is collected commercially for the aquarium trade, but the number of individuals taken from the wild or the size of wild populations is not known.
The P.turgidus populations in the wild are still healthy in suitable habitats and it is considered 'Least Concern' by the International Union for Conservation of Nature (IUCN).
In the aquarium
The P.turgidus is not commonly seen in the aquarium hobby, but we are seeing a recent increase in their availability and subsequent popularity. Although this is a species that will breed in captivity, most specimens available for sale are wild-caught.
The P.turgidus is a relatively shy and primarily crepuscular species, so it will be most active in the hours of dawn and dusk.
It must be provided with subdued lighting and a scape that offers an abundance of spaces in which it can hide. Driftwood, caves and Redmoor branches and lots of soft-leaved aquatic plants are perfect for creating an aquarium that is reminiscent of its natural habitat. Such a scape, in which the fish can take cover quickly, will actually encourage more active behaviour.
Stem plants, such as Limnophila sessiliflora (Asian Marshweed), are ideal for creating a soft, shady and dense scape which this species prefers.
The flow in the aquarium should be slow to medium and never overpowering. The tank should always be scaped in the aforementioned fashion.
Tank size
The tank should be approximately 80cm (31.5 inches) x 35cm (13.78 iches), with a height of 40cm (15.75 inches).
This translates to a tank volume of approximately 112 litres or 29.6 US gallons.
Water values
Maintain the following water parameters:
PH: 6.5 - 7.5 (in the middle is ideal)
Temp: 22-26°C (71.6 -78.8°F)
NH3/NH4+: 0ppm
N02: 0ppm
N03: below 15ppm *ideal
GH: 5-12 dGH
Tankmates
Although the P.turgidus is not as aggressive as most other members of Pao, it will attempt to eat any fish that will fit into its mouth and will severely (often fatally) wound larger tankmates. For this reason it is strongly recommended that they are kept as a solitary specimen.
The experienced aquarist may attempt to breed this species, but the behaviour between conspecifics is highly unpredictable.
Sexual dimorphism
There is no known method of determining the sex of this species for the home aquarist.
Notable behaviour
P.turgidus is capable of metachrosis, meaning that it can voluntarily change colour to camouflage against its surroundings.
They are known to jump from the aquarium if startled, so they must only be housed in an tank with a tight-fitting lid.
Feeding
One of the most important elements of keeping the P.turgidus is to provide a varied and balanced diet, in order to ensure that its nutritional needs are being met.
The P.turgidus is primarily piscivorous (feeding on fish), but it also eats small crustaceans (small freshwater crabs and shrimp) and other benthic animals, such as worms, in the wild.
Our preferred foods for this species include:
Thiaminase-free fish meat, cut into manageable chunks (read Feeding fish)
Gutloaded Earthworms
Gutloaded cockroaches, crickets and large woodlice
Aquatic snails (read feeding snails)
This species should not be offered cockles, mussels, clams, oysters or similar mollusks.
The teeth of the Pao turgidus do not grow as quickly as some other species of freshwater pufferfish, so the need to feed hard food items is greatly reduced.
Feed a ratio of 40% fish and 60% insects and worms. Owing to the inactive nature of this species, it does not require feeding daily. Three times a week is usually sufficient.
Feeding fish
Naturally, the P.turgidus preys upon a very wide selection of different species of fish in the wild. For this reason, we recommend alternating between as many different suitable options as possible.
Frozen Pond Smelt (Hypomesus olidus) are widely available and they are small enough for the P.turgidus to eat whole. Pond Smelt is a common choice of food and bait, so it can typically be purchased from all well-stocked aquatic stores and bait suppliers. Some species of smelt such as Rainbow Smelt (Osmerus mordax) contain thiaminase (read Thiaminase), so it is important to ensure that you know what species of smelt you're buying.
Generally, the choices of suitable fish at fish counters and markets are going to be quite limited, but there are several common options.
Larger species of freshwater fish such as Lake Trout (Salvelinus namaycush) and various Tilapia species are suitable, but these fish are obviously too big for the Pao turgidus to eat whole so they need preparing and cutting into manageable chunks. Discard of the internal organs, head and fins, fillet the fish and cut the fish fillets (scales and skin attached) into chunks small enough for the Pao turgidus to eat within one minute. These pieces can be frozen and kept for up to three months.
Insects and worms
Gut-loaded insects and earthworms are excellent sources of nutrition for this fish and are used to replicate the gut-content of the Pao turgidus' natural prey.
They are also ideal substitutes for freshwater crustaceans and are arguably far more nutritious than the saltwater crustaceans that most aquarists will be limited to at a fish counter/market.
Thiaminase
Some fish and crustaceans contain thiaminase, which is an enzyme that renders thiamin (Vitamin B1) biologically inactive. This means that the pufferfish can not absorb any thiamin from that food.
Thiamin is a crucial nutrient because it is an essential component of energy metabolism and it plays a key role in nerve, muscle, and internal organ function.
If a fish’s diet is mostly or completely made up of food items that contain thiaminase, that fish will develop a thiamin deficiency.
After consulting with veterinary professionals and other specialist keepers, we feel that avoiding foods that are known to contain thiaminase and replacing them with equally nutritious thiaminas-free food items is the safest, long-term option. This is the approach that we have taken with all of our pufferfish.
Feeder fish
We do not recommend the use of live feeder fish.
Feeder fish are often bred in squalid and overstocked conditions, where bacteria such as columnaris and mycobacteriums, and parasites such as Camallanus worms and Ichthyophthirius multifiliis (whitespot/ich) spread through the population very quickly.
Feeding feeder fish to your puffer greatly increases the chance of introducing pathogens to your aquarium, which can then infect your puffer and will require treatment. Feeder fish themselves are also usually nutritionally deficient.
The Pao turgidus species does not need live fish to thrive and will very often readily accept frozen-thawed food immediately after settling into the aquarium.
The use of feeder fish can also cause piscivorous to become very finicky and they may start refusing anything but live fish.
This is another reason that we strongly encourage you to begin the weaning process (read below) immediately.
Tips on offering prepared foods / weaning
Although some specimens will be reluctant to eat frozen-thawed foods at first, they can learn to accept it. The best training exercise is to offer nothing but live-earthworms to begin with and when your puffer is readily accepting those, start offering the same earthworms on forceps, building an association between the forceps/you and food.
When your pufferfish is accepting earthworms without hesitation from the forceps, you can then begin to offer other things, such as cockroaches, other insects and pieces of frozen-thawed fish. After several weeks, you won't need the forceps and your fish should readily accept any suitable foods that you drop into the tank.
Feeding snails
Snails should be fed to this species on a regular basis.
The shells of Melanoides tuberculata and other trumpet snails are too hard for P.turgidus pufferfish and may cause them to associate snails with pain/difficulty if they injure themselves trying to eat them.
The aforementioned species also lack substantial amounts of meat. The best snails are Physella acuta (bladder snail) and small/young terrestrial snails which are cultured for reptile and human consumption.
Filtration
This pufferfish is intolerant of poor water conditions, so a high level of biological and mechanical filtration is needed to deal with the amount of waste that this fish produces. However, they do not appreciate a strong flow.
Good filtration combined with excellent husbandry is essential to the health of this species. Frequent water changes must be carried out to maintain N03 (nitrate) levels below 15ppm; or as close to zero as possible. Extra attention should be afforded to ensure that the base of the dense scape is free from detritus.
Inflation
P.turgidus can inflate themselves when frightened or stressed.
They should never be provoked into inflating.
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