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Sexing and Breeding Pseudogastromyzon cheni

by Martin Thoene last modified Dec 15, 2006 09:05 PM

Article describing how to determine the sex of this species and details on breeding.


Sexing and Breeding Pseudogastromyzon cheni - article header


Pseudogastromyzon cheni will breed regularly in aquaria if given the correct conditions. Sexing them is quite easy once you know what you're looking for.


Sexing and Breeding Pseudogastromyzon cheni - Male and Female


You'll note that the female's belly is noticeably more full than the male's. It is convex and reflects the light back from it's centre. The female is broader in the belly at the point just behind the Pectoral fin rear origin.

Look at the nose of the fish. Sexually active male cheni have nasal tubercules increased in size. See them either side of the nose? Compare with the female. Females have very much smaller tubercules which do not increase in size when sexually mature. From underneath, you can only just see one pair.


Here, you can see that the tubercules are very visible.


Sexing and Breeding Pseudogastromyzon cheni - side view of Male's head

In a modified photograph, the weaponry is even more visible.

Sexing and Breeding Pseudogastromyzon cheni - Enhanced image of Male head


Females have small tubercules on the nose as well, but they do not grow like the males as they reach sexual maturity.


Sexing and Breeding Pseudogastromyzon cheni - Closeup of Female's head

In this photo below, the upper fish is the dominant male in the tank

The other fish looks like a subordinate male. You can see it has tubercules, but they are somewhat smaller than the other fish.

Sexing and Breeding Pseudogastromyzon cheni - Dominant Male at top

A male side-on is quite streamlined

Sexing and Breeding Pseudogastromyzon cheni - Male, side view

Note this one below has much reduced contrast between the light and dark body colours (see difference in dominant male above).

Females are generally this low contrast colour. Generally, they have a higher arch to the top profile of the body and are more full-bodied.

Sexing and Breeding Pseudogastromyzon cheni - Female, side view

The good news is that P. cheni are pretty good at working out who is who themselves. P.cheni courtship consists of the male dancing around the chosen female (often on the aquarium glass) and generally following her around. At some point the male will get accepted by her and then she will tend to follow him around.

Two fish squaring up to one another and trying to get on top of one another are generally males in territorial dispute. At these times colours will be intensified and may change to what we term "war paint". The upper area darkens and the sides go paler than normal. Males will raise their colourful dorsals as a display.

Sexing and Breeding Pseudogastromyzon cheni - Males fighting


The dominant male will tend to be the one breeding in a tank where you have several. He will dig a pit under a stone by sliding backwards off it and whooshing substrate away with his tail.

Here, a male slides backwards in typical fashion, from a chosen pebble.

Sexing and Breeding Pseudogastromyzon cheni - Male digging with tail under stone


The male and female then take turns in sliding backwards into the hole and eggs are laid and fertilized. The male then covers up the eggs. Several pits may be dug, but generally it appears they choose one only.

The eggs are quite large.

Sexing and Breeding Pseudogastromyzon cheni - Eggs buried in gravel

After around 14 days, tiny babies will emerge from the gravel. At that time they are just under 1/4" in length and will begin grazing on microorganisms on the tank surfaces.

Here are three fry who have recently emerged from the substrate.

Sexing and Breeding Pseudogastromyzon cheni - Babies on glass



Once the fish start to spawn, they may repeat the procedure every few weeks. Therefore, you may find that your tank will contain several sizes of babies. The parents are not predatory and the fry will grow up with them as long as there are sufficient foodstuffs available.

Here are babies that were born around three weeks apart.

Sexing and Breeding Pseudogastromyzon cheni - Two babies, 3 weeks age apart

Sexing and Breeding Pseudogastromyzon cheni - Different aged fry

Once the babies become active,they grow quickly.

At around 3/8" they have a prominent caudal peduncle eye spot, probably to confuse predators.

Sexing and Breeding Pseudogastromyzon cheni - 4mm long baby

They will take around 4-5 months to get to 1" (2.5cm) and reach 1.75"(4.5cm) in a year. Multiple generations of Pseudogastromyzon cheni will live together. Although easy to breed, their slow growth makes them of little significance from a commercial propagation point of view.

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