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Cichlid Fish Display Extensive Social Interactions


Neolamprologus pulcher (N. pulcher) is the breed of cichlid used in the study.

Credit: Dario Josi

A new study shows that cichlid fish reared in larger social groups from birth display a greater and more extensive range of social interactions, which continues into the later life of the fish. Researchers say this indicates the fish develop more attuned social behavior as a result of early environments.

The researchers also found that those fish raised in a more complex social environment have a different brain structure to those who experienced fewer group members in early life. If fish experienced the complex social environment for 2 month they had a larger hypothalamus: the area that contains most of the brain nodes of the ‘social behavior network’. They also had a larger ‘optic tectum’, which processes visual stimuli and could be related to the need to process more visual stimuli in larger groups, say researchers.

The brains of fish with enhanced social skills were not bigger overall than those reared in small groups; however, the ‘architecture’ within the brain was different.

“Our data suggests that, during development, relative brain parts change their size in response to environmental cues without affecting overall brain size: increasing certain parts forces others to decrease concurrently. These ‘plastic’ adjustments of brain architecture were still present long after the early stages of social interaction,” said study author Dr. Stefan Fischer, from Cambridge University’s Department of Zoology.

“Social animals need to develop social skills, which regulate social interactions, aggression and hierarchy formations within groups. Such skills are difficult and costly to develop, and only beneficial if the early social environment predicts a high number of social interactions continues to be critically important later in life,” he said.

For the study, published this week in the journal The American Naturalist, researchers used the Neolamprologus pulcher (N. Pulcher) breed of cichlid, primarily found in Lake Tanganyika — the great African freshwater lake that feeds into the Congo River.

N. Pulcher lives in family groups with up to 25 individuals, with one breeder pair and several helpers participating in territory defense and raising of offspring — known as ‘cooperative breeding’. To test for social skills, the researchers reared juvenile fish over two months with either three or nine adult group members, and observed all social behaviors at key experimental points.

These interactions included ‘lateral display’ — when one fish interrupts another by displaying their body side-on, sometimes as a mating ritual — as well as ramming, tail quivering, and ‘mouth fighting': a social display in which fish lock mouths to challenge each other over everything from food to mates.

Six month after this test phase, individual fish brains were measured to investigate the long term consequences of early group size on brain morphology, revealing differences in brain architecture.

The researchers say that one of the effects on social behavior in larger groups might be the perception of environmental risk. “In the wild, larger social groups of N. Pulcher represent a low-risk environment with enhanced juvenile survival. Being part of a larger, safer group may increase the motivation of juveniles to interact socially with siblings, enhancing the opportunities to acquire social skills,” said Fischer.

As perhaps with any social creature, Fischer points out that higher social competence and the ability to conform to social hierarchies may well stand the cichlids in good stead in later life:

“Group size for these fish stays relatively stable across the years, they have delayed dispersal. Remaining in a larger group means a better chance of survival. Fish reared in large groups showed more submissive and less aggressive behavior to big fish in the group, social behavior which greatly enhances the survival chances of smaller fish.”

Fischer added: “In highly social animals, such as cooperative breeders, almost all activities involve social interactions, where individuals need to adequately respond to social partners. In larger groups, these interactions are more common and individuals developing sophisticated social skills during childhood might highly benefit from them later in life.”

Source: University of Cambridge

Originally published here:

Posted May 15th, 2015.

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Adventures in Sudan and Zambia



Lake Mweru, Zambia. Photograph by Béla Nagy.

In the June 2013 issue, Béla Nagy writes about his adventures collecting in Africa. Two of the tougher places to collect were Sudan and Zambia, and he recalls his experiences there.

By Béla Nagy

Sudan: The Only Thing You Need Is Patience

Many years ago, large parts of Africa were what people would call terra incognita, unknown land. Today, much of the land is well known, but one of the few exceptions is the relatively unexplored Nuba Mountains region of Sudan.

It is prudent to always pay attention to the counsel of those who have been in Africa, and one common piece of advice is to allow plenty of time and exercise patience. This is especially important in Sudan.

After my arrival in that country for a collecting trip in 2010, the local agency I was dealing with began the complicated administrative tasks to provide us with the necessary permits. In the end, some members of our group were denied. We had also not been granted permission to visit some areas where there was potential for Nothobranchius habitats. Therefore, we had to take a risk and visit those regions without permits. We felt very lucky because, most of the time, we were allowed to pass through the countless military checkpoints smoothly and quickly and reach our planned destinations. This may have also been due to our local driver, who prayed to the celestial beings before each control point.

Sudan is vast, and one should allow plenty of time to get from one place to another. The poor road conditions seem to conspire against you in being able to reach the destination. We headed to the breathtakingly beautiful Nuba Mountains. Sudan achieved independence only in 1956, but since then, flirtations with democracy and military coups have been regular features of the Sudanese political landscape. Color-coded markings along the roads indicate the degree of risk of land mines. Few roads traverse these mountains, and many villages are accessible only by ancient footpaths or tracks. The absence of suitable accommodation in the Nuba Mountains made our tents a worthwhile investment. Although spent cartridges and scorpions were our standard companions wherever we pitched camp, we did not feel unsafe while traveling around the country.

We collected N. virgatus and N. nubaensis at several locations. The records of the localities of Nothobranchius species in central Sudan today indicate disjunctive and sporadic distributions of the species. Most of the known locations are in the foothills of the Nuba Mountains and have, presently, no obvious links. However, the Greek historian Herodotus noted that the 100 days of annual Nile floods occurred at the time of the summer solstice when no rain fell in Egypt, and he correctly interpreted the cause as heavy precipitation in the headwaters region of the Nile during that time of year. The highly fluctuating water levels of the Nile and the earlier presence of the ancient mega-lake provided more continuous and permanent connections between the presently known populations of Nothobranchius species in that area.

At the end of the day, the trip had been safe and collecting was a success, but it was at a time just before the planned elections in the country. A few months later, a new state was born when Southern Sudan reached independence after 21 years of bloody infighting. Tens of thousands of people had fled the violence.

Even after the countries separated, the security situation remained very unstable around the new boundary between the two parts of the former Sudan. Fighting, aerial bombing, and gunfire were frequently reported from the region along the new border and from the vicinity of Kadugli. We stayed in that city overnight and collected one population of Nothobranchius just outside of the city. A considerable part of our route led us in close proximity to the new border. Hopefully, the situation will soon be stabilized and allow further field trips into the region.

Discoveries in the Footsteps of Livingstone: Zambia

Zambia is a country one dreams about when thinking of visiting Africa—mesmerizing landscapes encompassing the very best of African wilderness, an astonishing diversity of wildlife, and people with genuine friendliness and warmth. Zambia is a landlocked country at the northern edge of the region referred to as Southern Africa, at quite some distance from both the Atlantic and Pacific oceans. Most of the country is part of the high undulating plateau that forms the backbone of the African continent. Several Nothobranchius habitats are known from Zambia, among others N. symoensi, a true beauty, which we have found at five localities.

In the foyer of the British Royal Geographical Society in London are some very interesting relics that greet the visitor. In the elegantly furnished lobby is a time-worn, carefully guarded treasure—the cap worn by Dr. David Livingstone when he traveled in the heart of Africa. The cap seems to embody the courage, tenacity, and determination of the original wearer. Livingstone was the pre-eminent missionary explorer of the Victorian era who criss-crossed Africa between 1841 and 1873, including much of what is now known as Zambia.

The area around Lake Mweru, which Livingstone discovered, was one of the major objectives on our collecting trip to Zambia in 2012. The Lushiba Marsh at the northern end of the lake had not been extensively investigated and, as Nothobranchius species are known from other drainage systems in the vicinity, it seemed likely to me that we might find a Nothobranchius species inhabiting the Lushiba Marsh. The drainage system in this particular area has been isolated from that of adjacent regions for a long time, so we speculated that any Nothobranchius inhabiting the marsh might well constitute an unknown species. However, the marsh is relatively difficult to access, and that is probably the reason for the lack of extensive ichthyological surveys in the area. It took quite some time for us to reach Chienge, a village at the edge of the Lushiba Marsh, but our efforts were quickly rewarded when the first site we stopped at yielded a new species of Nothobranchius.

We spent the evening at a new guesthouse in Chienge, with splendid views of Lake Mweru. The new state of the guesthouse did not mean it was of perfect quality, and there was no running water for the ablution facilities. On the other hand, we had delicious dinner prepared from the catch of the day from the lake. This wonderful dinner was in strong contrast to the meals of the previous few days that consisted almost exclusively of fritas, a kind of local fried cake that we could usually buy on the roadside. While fritas were quite tasty, the main problem was that quite a bit of sand found its way into the ingredients, and we had to eat them carefully. The peaceful dinner was also in contrast to the night we spent at another guesthouse the previous day, where the somewhat drunken local owner wanted to force us to go with him to the local night club, which we could only avoid after a lot of negotiation.

Discovering new fish species frequently requires dedication, and there may be many difficulties that one has to overcome, but the rewards make it all worthwhile.

Posted May 14th, 2015.

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Eco-Friendly Fishkeeping

You can use aquarium water to water terrestrial plants. Photograph by StockLite/Shutterstock.

Earth Day is a great time to carefully consider the impact our hobby has on the environment, and what we can do to lessen that impact. During my tenure here at TFH, I have learned about a few eco-friendly ideas that you might want to implement at home.

  • Aquarium water from a freshwater tank can act as a great natural fertilizer for plants. Whether you have a huge outdoor garden or a single plant indoors, it is worthwhile to use water taken during a water change for your plant instead of pouring the water down the drain. As a bonus, you can save money on fertilizer too!
  • If you don’t have plants, there are other ways you can save water. A good one is to use the water taken during a water change to flush your toilet. Just be aware that aquarium water can make your toilet look dirty.
  • Newer technology can help save energy while operating your aquarium. For example, LED lights use far less energy than other forms of lighting. You’ll also save money on your electric bill!
  • Choosing to buy captive-bred species instead of wild-caught ones will help the environment in many cases. For example, Banggai cardinalfish are on the verge of extinction in the wild, so buying captive-bred can literally mean the difference between preserving a species and helping to push it over the brink of extinction.
  • Along the same lines, only choose to purchase species you know you can keep. No matter how beautiful the fish is, if it won’t eat what you’re offering, grows too large for your tank, or is too sensitive to be kept in captivity, it is never the eco-friendly choice!

Do you have other aquarium-related eco-friendly tips? Let us know in the comments!

Posted October 12th, 2014.

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Keeping South American Annual Killifish

Photograph by Mike Jacobs.

By Charles Nunziata

There are several explanations of why most hobbyists are not aware of South American annuals and many have not seen one alive. First is their absence from consumer outlets and the relative lack of coverage in hobby communications. In addition, there is a widespread perception that all killifish have a short lifespan. Although this is not true of non-annual killifish, it is true of the annuals, and that fact alone is often a deal-breaker for some hobbyists. Lastly, killifish are considered to be difficult to breed and maintain, but this is not accurate.

General maintenance is not overly demanding, requiring only regular water changes and the provision of high-quality foods. Most annual killifishes can withstand large temperature variations, but as in most other fish, thermal shocks should be avoided. Mid-range hardness and temperatures in the 70s are ideal. Temperatures lower than 70 slow activity, and above 80 will accelerate aging. They do not thrive in poor water conditions and will not develop properly if undernourished, but any experienced aquarist to whom good aquarium practices are second nature will have no difficulty maintaining these species.

South American annuals tend to occupy all areas of a tank, are moderately active, and with some exceptions, are not aggressive to other killie or non-killie species. Rather, their color and finnage often invite aggression from other species. Non-aggressive species that are not overly active can safely be kept with most annual species. However, it is the practice of most killifish hobbyists to maintain South American annuals in species-only tanks, and better success can be expected if that method can be adopted. Tanks as small as 2½ gallons are sufficient for a few of the smaller species, and 5- or 10-gallon tanks are ample for all but the largest. Feeding is likewise straightforward. Live and frozen foods of all kinds and, with training, freeze-dried bloodworms and similar-quality foods will be readily taken.

The major difference between South American annual killifish and other hobby species is the time it takes for the embryos to develop. The eggs of non-annual fishes incubate and hatch within days or weeks, while annual eggs take months to develop and may well hatch after their parents are gone. The months-long uncertainty associated with not knowing whether a spawning has been successful is not compatible with everyone’s personality and is often the root of the idea that breeding these fishes is difficult. Killie-keepers have to be a patient lot.

For more information on breeding annual killies and what species are available, see my article in the June 2013 issue.

Posted May 22nd, 2013.

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When I Found A New Mosquitofish Without Knowing It

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 April 12th, 2013.

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