Although dwarf, Carinotetraodon travancoricus is a full-fledged puffer. It has all the peculiarities of this family of fish – some of them are unmissable, others are hidden to the eye of the observer, yet they are worth mentioning.
The most famous characteristic of the tetrapods (family Tetraodontidae) is their defensive reaction, where they inflate all over. This is done by expanding a part of the stomach into which they take in water or air. In doing so, the spines will eventually erect (this applies to species that have spines hidden in their skin – mostly marine species, not our pygmy tetrapod), making the tetrapod appear much larger; it can spurt the water it has taken up towards its enemy. The fact that they have no ribs also allows the tetrapods to inflate.
Quads don’t have scales, and they also lack pelvic fins. The dorsal, anal and pectoral fins are in constant motion, the caudal fin serves as a powerful rudder. The constant swirling of the fins is unmistakable – as is the dexterity of the quahogs in swimming. They hover in the water like a helicopter, even reversing and turning on the spot. If they decide to lunge at prey or an enemy, the movement is lightning fast.
Last but not least, puffins impress with their gaze – they can move their eyes independently. Sometimes you can’t help but get the impression that while they are examining the morsel you’ve thrown them with one eye, they are constantly watching with the other eye to see if that big, inscrutable creature behind the glass is going to do something untoward. Sometimes they simply roll their eyes at me.
There is a lot more interesting things that could be written about puffers, about their intelligence and behaviour in general, about the environment they live in, about their venom, etc. But to get to the breeding of this dwarf helicopter, I’ll just mention one last interesting thing – the teeth. They are set into a sort of plate, actually four, as the genus name suggests. The plates continually grow back during the life of the fish and must be ground off when biting suitable food. Puffers are food specialists, consuming molluscs and little other food. We will discuss how to deal with feeding in the aquarium later.
Genus Carinotetraodon
The species this article is about was described in 1941 under the name Tetraodon travancoricus. After that, it also bore the genus name Monotreta for some time, until it was finally reassigned to the genus Carinotetraodon, which was created in 1957. It currently includes 6 species, including several really small tetrapods described only in recent years. Only four species are more or less encountered in aquaria, and most of them very rarely. However, the dwarf quadrats are gaining in popularity and are gradually displacing the larger and more demanding species, which I think is only good.
Carinotetraodon travancoricus is native to India from the states of Karala, Malabar and Travancore. A very similar species from the same region is C. imitator Britz & Kottelat, 1999. It is reported to be slightly smaller, but otherwise both species are imported together and confusion in imports cannot be ruled out. They differ slightly in colouration.
I have seen another newcomer, C. irrubesco Tan, 1999. This species is slightly larger, growing to 4.5 cm. It comes from the slightly acidic waters of Sumatra and Borneo. It is very similar to another relative, C. lorteti, which is probably the most common representative of the genus in aquariums. It grows to a length of 6 cm and is striking for its red eye colouration and also for its striking sexual dimorphism.
This is the peculiarity of this genus in general – in fact, unlike other tetrapods, there is one very striking difference between the sexes. I will come to this in a roundabout way. The name of the genus Carinotetraodon consists of the common name tetraodon (from the Greek), but we also have the word carino-. This comes from Latin and means crest, keel. Loosely interpreted, we might think that the members of this genus are perhaps some kind of “punks” – no, wrong, comb is misleading in this case. It is the keel that is formed by the males during impaling (see below for details). This conspicuous feature is common to all (male) members of the genus and distinguishes them clearly from other quatrefoils.
Description and sex differentiation
Carinotetraodon travancoricus certainly deserves its place among the dwarf species, reportedly growing only 3.5 cm. A far more common figure is a length of just 2.5 cm. The largest male I have is exactly 25 mm, maybe a hair more.
The colouration is typically “pufferish” – a light ground with irregularly scattered dark spots. The body shape is also typically barrel-shaped.
It is easy to distinguish males from females – provided, of course, that the fish are adults. The female is rounder, the male more elongated. The latter, moreover, flattens the body during impingement so that it has a sort of keel at the base of the body and pulls up the back into the form of a ridge – meaning the ridge of the mountains, not the jagged one for combing 🙂 You’ll notice the change from round to at least a hint of vertically flat fish – then you’re dealing with a male. At that point he’s usually upset and showing off to a rival or to the females. At the same time, the black longitudinal stripe on the belly, another identifying feature, will be highlighted. Most of the time the stripe is faded and faintly visible, but even the female has a hint of it when she is excited. But if it’s prominent, it indicates a male.
A sign that’s noticeable even when completely still is the male’s “wrinkles”. They are more obvious the older the male is – the female has nothing like them, so it is easy to distinguish older fish. They are most noticeable behind the eyes, but can also appear on the flanks.
The colouration of the two sexes is also slightly different, but this feature can only be used if the fish are completely cool and unstressed, and properly coloured. Males have more yellow on their tail and fins. They usually have fewer spots on their backs and sometimes the pattern merges into an almost uniform brownish hue, the spots fading. The females are more “plain”, i.e. the ground is cream, there is much less yellow and the spots are more noticeable, never disappearing. In females, there are sometimes small spots scattered among the normal spots – it is questionable whether this is a different colour variety of this species, or a very similar relative, Carinotetraodon imitator. However, the tiny spotting was only observed in females.
Rearing in the aquarium
Considering its size, this is definitely a fish that will be content with a small aquarium. However, a hygienically arranged 10 litre element will certainly not be the right home. Carinotetraodon travancoricus doesn’t need much swimming space, but it does need a rough bottom surface, hiding places, dense plant growth – it simply needs an environment where it will always have something to explore. It is a lively and active fish that may not swim much, but it must never get bored. It spends all day exploring, examining and considering whether this or that object or animal is worth opening its mouth and biting. Since the bite is lightning fast and very powerful and is performed by moving the whole body, it requires a lot of energy. Therefore, this puffer often thinks before it moves. It is not familiar with test bites.
Because of its biting technique and biting tendencies in general, it is definitely better to keep this species alone. It can nibble the fins of its tankmates; it is said to like doing this and to be very efficient. On the other hand, it suffers from constant disturbance and cannot feed sufficiently. Carinotetraodon travancoricus moves in all layers of the water column, so this is not the route to matching requirements with other fish either. Face it, if you want to enjoy the behaviour of this interesting little creature, then definitely in a species aquarium.
In a tank with a volume of about 15-20 litres you can keep a group of juveniles – later, when they reach maturity, it will be necessary to separate them and keep only one male and two females together, or a pair (more females means less aggression, but this does not exclude that in preparation for spawning the male will not dispose of the excess fish).
Not only males but also females are aggressive; however, they usually occupy lower ranks in the group hierarchy. In larger aquariums it is possible to keep a group for a long time, thus spreading the aggression over more individuals. The territorial demands of this species are less than usual for quadrats, but do not underestimate its aggressiveness. There is always the possibility that one of your fish will “go crazy” and start terrorizing the others – there is no way to prevent or predict this.
If these fish start to think about spawning, then there is a nervous period during which life-and-death battles between males are the order of the day. I have literally seen such a fight with my own eyes. It’s not an innocent fight, if the weaker one doesn’t run and hide, he won’t make it out alive, unfortunately. That’s why it’s better not to keep multiple males together unless you have at least a 30 litre aquarium. Of course, it is important to have a structured space so that the whole aquarium is not visually controlled by the strongest individual. This will allow an undisturbed and happy life for the weaker ones.
Keeping in a group is very interesting, we can watch the interactions of the individuals and there is always something going on in the aquarium. When young, these fish are peaceful and tolerant. But once the strongest male starts to drive the others away from the food, the idyll is over.
As far as water requirements are concerned, they are nothing special. This species is one of the few tetrapods that is truly freshwater. It prefers water with a pH around neutral or slightly alkaline. The water should not be very soft, but otherwise the hardness does not matter. A higher temperature of 23-28 °C is preferable; but to be honest, I have had quahogs for a long time in an aquarium without heating (20-26 °C depending on the season) and they are in good condition, never having had any disease.
One more note on the water – it must of course be as clean as possible, i.e. free of ammonia and nitrites (do not put quads in a freshly set up aquarium!) and with as little nitrate as possible. While this should not be a problem, as there are many plants in the ideal aquarium for this species, on the other hand they also feed on nutritious food. Sticking to the rule of about 4 litres per fish is therefore advisable, also for territoriality reasons. Quahogs are sensitive to poor water quality and are then prone to disease. They do not have a body covered with scales and are more easily affected by various fungal diseases. Whatever affects them, let’s keep in mind an important fact – like suckers, they are very sensitive to copper, which precludes the use of many drugs!
Problems can arise with the technical equipment of the tank – the quatrefoils are curious and examine everything closely and closely. There have been cases of fish being burned by the heater and also sucked into the filter. The smaller the fish, the more we need to be concerned about its safety!
If we follow the basic rules of aquarium care, we will find that this is indeed a hardy and undemanding species.
Food
Feeding is a chapter in itself – Carinotetraodon travancoricus is a typical “target” fish. It first examines the chosen object, sometimes from different angles, considers it, takes aim. Only then does it act. We can only provoke a lightning attack if we feed a group of fish at the same time and use a well-known food – for example, fish can react to tweezers with frozen patches by jumping above the surface after 2 weeks. However, if the fish are calm or encounter something unfamiliar, they enjoy the food and take a long time to prepare for it.
The best choice for food is, of course, snails. Since this species of quahog does not bite the shell, but attacks the body of the poor snail directly and basically sucks it out of the shell in one stroke, we must choose the size of the food well. A roundworm that is too large will mortally wound a fish with a single well-placed bite, but it cannot eat it. It cannot take a proper bite – it must always suck the whole body and then roll it around in its mouth for a few seconds and bite before swallowing it. Small crustaceans and other smaller gastropods are most suitable, with the exception of members of the genus Physa. These my puffers can’t handle, and rarely can they hit them so well with a single bite that they suck them out. They can’t get an injured snail out of its shell, where it retreats.
Just in case, I recommend keeping a sentry shrimp, Neocaridina heteropoda (aka N. denticulata sinensis in the old fashioned way) in the aquarium. They can eat the remains of the snails and, strangely enough, the quadrats don’t attack them. And if they did, the shrimp are a quality food and, since they reproduce easily, serve as an insurance supply of food for, say, vacation time.
They will also leave large snails alone. While I haven’t tried the bladderworms (Pomacea bridgesi), I have tried the neritina – and they have held up. However, the fish did take a long look at them – they are very good at knowing what is potentially edible, and of course the snail’s appearance is stored in their memory.
We can offer our fish other food besides snails – but keep in mind that this is always a substitute and snails are necessary for a healthy and happy life. This species eats good quality frozen and live snails with gusto. They do not eat frozen cyclops etc., which are too small, and frozen coretails and frozen adult artemia have also not met with even minimal interest. However, live plankton and especially black mosquito larvae have generated a lot of enthusiasm; live threadworms have also been successful. Nauplii artemia are an interesting food for juveniles and, after a little adjustment time, for adult fish as well – be careful that they are freshly hatched, they lose their nutritional value quickly. When hunting for live food, the fish are entertained and can gorge themselves. Perhaps the best food, with the exception of snails, is live daphnia in my opinion. The unusual movement in the aquarium may have spooked the fish at first, but they got used to it and with a little practice learned to hunt daphnia. The daphnia are constantly bouncing around and the four-toed daphnia were not successful at first with their aiming technique. Since the daphnia has a rather hard “skin”, or shields covering two sides of its body, the tetraodon has to use its teeth and can be heard chewing the daphnia. The “skin” is then spat out. It is therefore a suitable substitute for snails to some extent, but the daphnia is not very nutritious.
Although dwarf puffers don’t often have problems with overgrowing teeth, as is common with their larger relatives (they also don’t bite shells, unlike them), snails still have an undeniable place of honour in their diet.
I do not recommend artificial food at all. It is possible that the puffers would get used to pellets, although I do not consider it very likely for this dwarf. Either way, it’s not the food they need and deserve.
Puffers are very voracious. They can stuff themselves to bursting. We mustn’t overfeed them, but on the other hand it’s quite advisable to put them on an occasional day or two of starvation. Be careful when feeding frozen food, it is advisable to let it thaw in the water for a few minutes beforehand and warm up to the temperature of the aquarium water. Ingesting large amounts of cold food could cause gagging or other problems. When feeding live food, the fish, stuffed like a barrel, keeps aiming and killing more bites, spits them out after a futile effort to suck them in… and so it goes on. And again the shrimps come in to clean up.
It sometimes takes a long time to get a shrimp used to new and unusual food, or to find out what they like in freshly acquired fish. Don’t be alarmed, feeding these oddballs just isn’t quite that easy.
Breeding
Carinotetraodon travancoricus has been successfully propagated several times in the aquarium. Hints of impingement and courtship can be seen quite often, but spawning occurs very rarely, so successful breeding is still a great success so far. The most famous breeder of this dwarf is a certain Ren from Japan, who bred these fish in a 17 litre aquarium and documented the entire breeding process extensively. Unfortunately, his website is no longer functional. Links to his many experiences can be found on all sites and discussions dealing with dwarf minnow breeding. Ren popularized the breeding of these fish and I learned the most from his site.
So what does breeding look like? It can be triggered by a temperature rise of a few degrees; of course, the fish are ready and in excellent condition (good feeding!). After several days of restlessness, accompanied by fights between the males and also violent “clarification of the situation” with the female, spawning takes place in a hidden place among the plants. This species seems to favour crevices or otherwise sheltered places – and so has been known to spawn among rocks, under anubias leaves, in clumps of Java moss. Java moss is generally recommended as a spawning medium. The fish do not deposit their eggs, they simply rub over the plants.
Neither the eggs nor the spawn are cared for by the pair, so it is possible to see the brood in the parent tank. However, the male is vigilant in guarding his territory and attacks the female. Spawning usually continues for several days in a row (only a few eggs are added per day) and may recur after a break of several weeks. Egg development lasts about 4-5 days and in another 5 days or so the spawn will disperse. Funnels should be fed first, after 5-7 days we can start feeding artemia. We have to sort out the fry as they grow older, otherwise their biting ability starts to show. Otherwise, rearing should be easy.
This dwarf is becoming increasingly popular with aquarists. Carinotetraodon travancoricus may be tiny and look harmless, but don’t get it with the same recklessness as, say, neonates. It is definitely not a “snail eater”, suitable for the community aquarium as a fun addition. It’s a personality, and if you give it a chance to express itself, you’ll fall in love with it very quickly – I’m convinced of that.