Hypancistrus sp. L399

Photo: Haakon Haagensen


By now, most enthusiasts will have noticed the level of uncertainty that surrounds the proper identification of the wormlined Hypancistrus forms from Belo Monte, Rio Xingu, Brazil. There appears to be evolution in the making with new forms separating into new species, and these forms also prove to be highly variable when bred in captivity. Hypancistrus sp. L399 and Hypancistrus sp. L400 were initially presented as two separate forms from the same area, but it has later turned out to be very hard to separate these two l-numbers from each other due to the variability within both of them. They are among the most beautiful of all l-numbers with their black markings against a light body, and they are kept by numerous breeders worldwide. Because of their similarity to other Xingu-based forms, crossbreeding is a high risk. For now, they are not allowed for export from Brazil, so captive breeding stock is required to maintain the existence of these beauties in the hobby.


Name: Hypancistrus sp. “L399”

Trade names: L287, L399,

Origin: Rio Xingu, Brazil.

Maximum size: 14 cm / 6”

In the original presentation by Werner, L399 was presented as a slightly more elongate, bigger (12-14 cm) form than L400. Also, L399 is usually showing a pattern of stripes and short lines, not unlike L66, whereas L400 may often show a pattern of spots and blotches. Wild imports have since shown a huge variation where individuals overlap these traits in every way. It seems likely that they all represent the same species, which could even turn out to be the same species as L66, L173 and L236. The differences in appearance may be the result of local adaptations to certain conditions in the rapids and pools where these fish are found. Compared to L66, L399 has an even more elongate bodyshape, and the caudal fin is usually more forked too. L66 grows bigger. Compared to L174, the spotted varieties of L399 has bigger eyes, a more elongate body and a larger adult size.

Although it’s difficult, one should always strive to keep separate lines of L399/400 apart.

They need an aquarium set up consisting of lots of hiding places in the form of rocks, wood and of course specially made caves that suit their measurements. In these the males will eventually guard their offspring. They prefer water that is fairly warm (27-30 C), soft and slightly acidic. Most of all it should be well oxygenated and clean, so a good filtration system and frequent water changes are essential. Among themselves they are fairly peaceful, although males may quarrel for caves and females can sometimes be badly injured or even killed during the breeding-trapping in the male’s cave. Males develop longer odontodes on their pectoral fins and on their cheeks, and have broader heads. Hypancistrus are mostly carnivorous, so a selection of crustaceans, insect larvae and fish meat should be offered along with high quality dried foods that also contain some vegetable matter.

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