Freshwater tropical fish.

 On the classification of these fish.

There are other species of Pangio that are sold as Kuhlii, they look the same and have the same requirements, but they are not really kuhlii.

Within the Pangio kuhlii there are 3 recognized subspecies: P. kuhlii kuhlii, P. Kuhlii sumatranus and P kuhlii myersi.Pangio kuhlii in any of the available options.

The Pangio kuhlii is a peaceful, eel-shaped fish that likes to roam the shady parts of our fish tank.

It is native to Malaysia, Thailand, Indonesia, Singapore, Vietnam, Sumatra, and Borneo. The specimens acquired in Uruguay are obtained from their reproduction in captivity. At first glance it reminds us of a viper. Hence, it is also named Kuhlii viborite. It has fins, but they are small and transparent, which often makes them invisible. It also has its body covered in scales (except the head), which are very small and difficult to notice by touch. These scales are covered with abundant mucus, which it needs to protect itself when burrowing. The mouth is down (as in all bottom eaters). It has 4 pairs of barbels. 

Being a very sociable animal, it has no problems living with other species: it gets along with all of them! Now that the ideal is to keep it with animals from Asian biotopes, so that the water conditions are optimal. As it is a fish with crepuscular and nocturnal habits, if the aquarium does not have shady places, it will only come out of its hiding place at night. It can also happen that we spend several days without seeing them. Let's take into account that in its natural habitat the waters are muddy, so visibility is limited. The crystal clear waters of our aquarium, added to the shadowless lighting, make them feel uncomfortable.

They like to immerse themselves in the substrate of the fish tank, so it is convenient to install a sector of sand so that they can do so without hurting themselves. Another possible option is to place a test tube lying down and half buried at the bottom; they will always be there inside and we will not run the risk of getting hurt by contact with the stones.

It is not a school fish, nor are the different species of Discus. Just like those, he likes to live accompanied by others of the same species. Also of the Pangio Kuhliis we must say that they are, then, gregarious .

So, our advice is that you do not add one specimen to your fish tank, but at least two specimens. They will come to a favorable interaction for your life.

The dark bands are wide and do not continue ventrally.

The eyes are small, covered with a transparent membrane

and below them it has 1 erectile spine,

hence its popular name of spiny-eyed loach .

Feeding.

The Pangio Kuhlii is a scavenger and detritivore. Thus, it collaborates with the hygiene of our fish tank. If we choose to feed it specially, because we have a group of them installed alone, we must treat them like any omnivorous fish that feeds on the bottom. It accepts all kinds of commercial food, as long as it is varied, as is the case with other fish. They also like fresh or freeze-dried tubifex, and all kinds of live food: mosquito or fruit fly larvae, microworms, brine shrimp, etc.

To optimize their health it is convenient to feed them late in the afternoon. Also include pellets that fall to the bottom, or specific food for bottom fish in their diet. Likewise, they enjoy if we supply them with food from the so-called week end, since they settle on the substrate of the aquarium. Although feeding, being in a community aquarium, does not present great demands, we must fully adapt it to their needs, especially if we intend to reproduce them. Keeping them in water in good conditions and ensuring the correct feeding, they will not get sick. If you get sick, medicate carefully (in a separate container): it is not easily resistant to chemical products or salts.

sexual dimorphism.

When they are not in the reproductive stage, sexual dimorphism is almost non-existent. This, added to the fact that it is difficult to see them in the light, makes it difficult to sex them.Females usually have a larger body and a wider ventral area.In males, greater muscular development is observed in the upper part of the body. Also males have larger, longer and more colored pectoral fins (color on the edges of the fins).

In the caudal fin they present a spot (in the upper part).

The ventral part is pink.

Reproduction.

The Pangio kuhlii can reach between 12 and 15 cm, males and females respectively. Before that, at 6 cm long, they are already in adulthood, and therefore, reproductive. To motivate them to reproduce, we must place about four pairs together. They are oviparous. The female lays between 300 and 400 pale greenish eggs. Before spawning, the pairs start swimming close together and fast. They leave their lower swimming zone and swim close to the surface, in a playful and agile courtship. The male embraces the female, who releases the eggs that he immediately fertilizes. They remain floating on the surface of the water until they adhere to the roots of floating plants.

With water between 26º and 28º, the eggs hatch within 30 hours. They must be guarded against predation by their parents and other pairs of Pangio kuhlii.

Removing the fish would be too obvious an intervention. It could cut off the intention of the other couples to make their bets.

So to protect the eggs, we must remove them with their plants, to another aquarium in the same temperature and water conditions.

The breeding aquarium.

The Pangio Kuhlii or simply kuhli , as it is usually called, is a resistant and long-lived fish that does not offer us problems and is not delicate to care for.

What is dangerous for him are the openings of the aquarium and the pipes of the filters. 

This perspective changes when we want to reproduce them. Here comes the downside: getting them to decide to reproduce. So, we must take several precautions, mainly in what has to do with the aquarium. We must allocate a fish tank for them alone. A container of standard proportions, between 60 and 100 liters, is fine.

The ideal is to provide it with a floor of silica sand at least 10 cm thick. In Uruguay it gets complicated like this. Then we can put freshwater sandbox sand, as I always call it. It has to be this sand, remember that our beaches are useless. In that sand you bury, with an inclination of approximately 45º, the glass test tubes that we mentioned before. You place them so that only the mouth and a bit of their body are visible. Next to each mouth it is convenient to place a stone, to make the site more shady and reliable. And right there, between the stones and the tube or next to them, plant some echinodorus uruguayensis or amazonicus or another plant of a similar format. 

On the sand, you must distribute 1 liter of pebbles of small granulometry, grouped in 6 or 7 places.

All of the above will help the kuhli, by nature skittish and fearful, to find the twilight that makes it happy to be swimming free, instead of hiding. We must also cover the fish tank. The surface should be almost completely covered by plants. For primary awning I recommend the Lemna minor (duckweed), which spreads quickly, filtering the light. But duckweed lacks the effective roots to support a good number of eggs.

Below the duckweed, you must place another floater of higher density. Personally, for this I like riccia fluitans, which also develops and maintains very well, with the help of duckweed.

At the time of breeding, the female is larger than the male

and remains transparent, sometimes revealing her green ovaries from the eggs.

The aeration must be smooth because in its natural environment the waters do not come from mighty currents. In that space where bubbles rise, it is good that there are no floating plants. Remember that their intestinal mucosa performs respiratory functions, as is the case with other fish, which absorb oxygen directly from the air. Then, you must find a certain space through which to lean out to breathe. It does this only once a day, usually at dawn. In its natural habitat, it is a necessary resource due to the frequent lack of oxygen in the water. In this aquarium that we set up especially to try to reproduce them, we must always keep the water the same, and always in the conditions that they best assimilate. There can be no calcium in the water.