Polycentrus schomburgkii: Insights from Breeding and Rearing a Rare South American Species

When I received interesting fish from Guyana from my friend in Switzerland, I was overjoyed. Next to the beautiful two pairs Crenuchus spilurus mi Pascal SEWER dedicated a beautiful young pair of Polycentrus schomburgkii. The fish I last saw in the 1960s were back in Czech Rep.! I didn't know which fish I should be more excited about. Crenuchus spilurus I have previously raised, but the spiny fish were a great unknown to me.

Old acquaintance

The Polycentrus schomburgkii has been known to European aquarists since 1907, when it was first brought to England by Captain VIPAN. In 1909, J. P. ARNOLD also brought it to Germany.

It is a fish that lives a solitary life, the male is larger than the female and grows according to conditions 7-10 cm. Fish change color both according to their mood and the environment in which they live. During the breeding season, the male is a deep black. We keep them with equally sized fish; I placed all the donated fish in a 40-liter aquarium densely planted with plants and equipped with various hiding spots, tubes, pots, and other ceramic creations. The fish live hidden away, becoming somewhat more active in the evening. Ideal for them are also the leaves of plants on the surface or directly floating plants, as they feel much safer in this environment. When filtering, we ensure that the water flows only gently.

Homeland

In nature, fish typically live in rivers with black water in the region of northeastern South America, in the countries of Guyana, Venezuela, and Trinidad. In the areas of occurrence, hardness is barely measurable, pH fluctuates between 4.8-6.2, temperature is between 26-30°C. My fish came from Crique Gabriele in Guyana.

Feeding

All piranhas are piscivorous fish, which in translation for aquarists means that they feed on fish or their parts. The ideal are young livebearers, but they also gladly accept daphnia, black mosquito larvae, water fleas, and a number of other creatures that we catch in forest puddles. They will catch a live fly that we throw on the surface, as well as chopped earthworms. Frozen food only interests them until it sinks to the bottom.

Aquarium

It doesn't have to be large, just 40-60 liters for one pair, densely planted, bottom made of finer sand, numerous hiding places. I use regular tap water from České Budějovice, slightly acidic, temperature around 25-26°C.

Breeding

28-30 °C, considering the conditions in which fish live in nature, the figure of 18-20°dH seemed too high to me. I used the usual refined tap water from České Budějovice with a small admixture of peat and a total conductivity of 190µS/cm, pH 6.3.

The fish are spawning in the little cave, in my case in a flower pot with a punctured entrance hole on the side. The eggs are around 500-600 pieces, hanging on a thread about 0.5 mm long and thin, hatching in 3 days, free swimming on the 7th-8th day.

During spawning, the female lays several eggs in succession, followed immediately by the male, who fertilizes the clutch. The actual spawning lasts 2-3 hours. The male in the aquarium has such respect that the other inhabitants do not even approach the flowerpot. Literature states that the female should be removed after spawning. Because my aquarium had plenty of hiding places of various kinds, including dense plant growth, the entire aquarium population continued to live happily even after spawning.

Just a dominant male Crenuchus spilurus, which in the meantime spawned with one of the females in the ceramic tube did not leave it for a moment, because otherwise it was very intensely pursued by the male of the spiny fish. The second male also Crenuchus spilurus was mostly hidden in the tube, was pursued by males of both present species. The fish, however, stayed throughout the care of the young spiny loach in the second half of the aquarium. The fry is very small, grows very quickly. I started feeding it with water fleas and daphnia, after 4 days also with fine brine shrimp nauplii and further with live food of appropriate size.

Images

1. Adult male in resting coloration.
2. Female about 2 weeks before spawning.
3. Dense aquarium with a volume of 40 l.
4. The adult male spends most of the day in its hiding place.
5. The male carefully guards the clutch.
6. The male is darkly colored during spawning and caring for the fry, and leaves the flowerpot only when foraging for food.
7. After the fry has been released, the male is constantly nearby.
8. The sand at the bottom provides an ideal refuge for fry.
9. It is ideal for the fry to "swim" in the feed, as this promotes the best growth. In our case, a three-month-old individual among the breams.