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When I Found A New Mosquitofish Without Knowing It

by TFH Magazine on April 12, 2013 at 12:41 pm

Ronny Lundkvist

Photographs by the author

This tiny brook at Jhuguañaró, Paraguay was where the author collected speckled mosquitofish.

The speckled mosquitofish (Phalloceros caudimaculatus) was one of the earliest livebearers in our hobby. It was described in 1868 as Girardinus caudimaculatus by Hensel. Later the name was changed to Phalloceros caudimaculatus by Eigenmann in 1907.

It was originally described from southeastern Brazil and its range is in eastern Brazil from the Rio de Janeiro along the coast down to Uruguay and Rio de La Plata.  It is also present in Paraguay.

The male reaches a length of approximately 3 cm (1 inch) and the female can grow up to 6 cm (2¼ inches).

A male (bottom) and female (top) Phalloceros harpagos from Jhuguañaró.

It is not a tropical species and is best kept at 18° to 24°C (64° to 75°F). However, it can withstand being kept for periods in both lower and higher temperatures. When kept at high temperatures all year around, I have found that it does not do well.

Otherwise it seems easy to keep and it takes both dried and, of course, live foods.

Earlier at least two subspecies were available in Europe: the golden tail spotted livebearer (P. caudimaculatus auratus) and the golden spotted livebearer (Phalloceros caudimaculatus reticulatus auratus). These are seldom seen nowadays.

The same concerns the original speckled mosquitofish.

A Trip to Find the Speckled Mosquitofish

In November 1995, which is early summer in the southern hemisphere, I went to Paraguay in order to look for livebearers, among other fishes. I had expected to find five livebearing species, but I only found three. One of these was of course the common guppy, which may have been released by some aquarist. The other two were the speckled mosquitofish and the rare Phallotorynus victoriae. Information concerning the distribution of the latter was very scarce in 1995 as I wrote in my March 2004 TFH article.

I went to a friend´s country estate at Jhuguañaró close to Guarambaré and 25 km (15½ miles) southeast of Asunción, the capital, in order to look for fish. Narcissus, who was a tenant close by, told me that there were tiny fish in a small brook emanating from a well in the forest. I brought the net and went to the so called Selva de los Monos, the Monkey Forest, where a kind of shy monkey, called kadjara by the local people, lived. The monkeys used to have the insolence to throw their excrements at intruders. Either they were having a siesta or showed respect for a foreign aquarist, as they did not bother me. After many hardships in the marshes we finally arrived at the brook where I found the longed-for speckled mosquitofish. The water temperature was 23°C (73°F), dH 2, and pH 7.6. The bottom consisted of gravel and stones. Plants were absent in the water.

Returning to Paraguay

As the fishing was successful, I returned to Jhuguañaró in November 1996 in order to look for these livebearers once more. My arrival was preceded by a period of heavy rain storms.

After a toilsome walk through the Monkey Forest we finally came to a torrent that the year before just had been a small brook. Masses of sand had filled the cavities where the fishes used to hide. There were no speckled mosquitofish.

I came back some days later, as the tenant Narcissus suggested that we should go deeper into the forest. I knew what was to be expected—mud to the ankles, thorns at the height of the knees, branches in the face and, moreover, mosquitoes en masse. Repellent did not help, as I transpired enormously. My guide showed me herbs that the local population used as medicine since time immemorial, from remedies against heartburn to diarrhea, but nothing against mosquito bites.

Suddenly I saw two monkeys at the top of a tree. It must have been an omen, as we did not walk far until we found a small well. I saw something at the surface and quickly I grabbed the net. There it was the speckled mosquitofish. The water temperature was only 22°C (71°F) with a pH 6.9, but the air temperature was 33°C (91°F). The species seems to prefer small brooks and wells in the shade—otherwise known as slow flowing, cool water—at least in the places where I found it.

A New Discovery

I brought back specimens of the speckled mosquitofish both in 1995 and 1996. As the coloration differed from that of the original description, I sent some specimens to the Swedish Museum of Natural History in Stockholm where they labeled them as Phalloceros species NRM 338 11.

I had the species for some years, but I think I kept it too warm. They did not do well. It is hard to have a winter season in the tank when you live in an apartment with central heating. The temperature in your apartment depends to some extent on that of your neighbors. Perhaps it should be kept outdoors in the summer, if you live in the temperate climate zone. Formerly, when aquarists had problems with the temperature being too low, the environment was more favorable to the speckled mosquitofish.

However, the most interesting thing about my catch is that it later showed up to be a new species. In 2008 Paulo Lucinda of Brazil, published an accurate revision of the genus Phalloceros. He described 21 new species belonging to the genus. Among these species we find Phalloceros harpagos. He analyzed a lot of specimens when describing the species, including NRM 338 11—the specimens that I sent to the museum already in 1995.

So watch up when you have found something new and put it in the tank!  Who knows, perhaps you have tankmates waiting for description.

Works Cited

Lucinda, Paulo, H. F. (2008). “Systematics and biogeography of the genus Phalloceros Eigenmann 1907, with the description of twenty-one new species.” Neotropical Ichthyologi, 6 (2): 113-158, 2008.

Note: The fish in the pictures originate from the same site as those that I sent to the museum. It is highly improbable that the very limited habitat where I collected the fish should hold more than one Phalloceros species.

Posted in TFH Extras by TFH Magazine on April 12th, 2013 at 12:41 pm.

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