Amphilophus xiloaensis

Amphilophus xiloaensis

Amphilophus xiloaensis was described by Stauffer in 2002. This species is named after the crater lake where this species occurs, Laguna Xiloá.

Description

Amphilophus xiloaensis is perhaps the most variable within the group of Midas cichlids. In addition to the normal grey, there are also completely white, yellow, orange and even red individuals. In addition, there are all kinds of intermediaries. Cichlid breeders call this “marble or blotched”. And although they all seem like breeding forms, all these variants really occur in nature. In fact, this variety is why this group of cichlids are called “Midas cichlids”, after the fairy tale of King Midas, where everything turned to gold that he touched. For more than 40 years, research has been conducted into this special group of cichlids and little by little the mystery has been unraveled.

At first, it was thought that all these shapes intersected randomly. aquarium observations seemed to confirm this, but recently in-situ observations (on-site observations) showed something very different. It has been established that there is not only a clear preference for their own physique (with corresponding eco-type) but also that the animals within these types show a clear preference for their own colour (Elmer 2009). And that is interesting because the animals are after all not aware of their own colour. This means that the animals are probably already more different from each other than just the outside would suggest and that the different colours are fast becoming independent species.

Evolution thus caught in the act. And although still at the stage where crosses occur, we clearly see here the processes of speciation, driven by a combination of natural and sexual selection. The original ancestors who ended up in these crater lakes in the past split up. Despite or thanks to all this variation, the majority (for us) can hardly be distinguished from Amphilophus citrinellus and/or Amphilophus amarillo. According to Stauffer’s diagnostic key, the eye diameter of Amphilophus xiloaensis should be smaller than that of Amphilophus citrinellus and to distinguish it from Amphilophus amarillo we would even have to cut the fish open. Probably a bit too much to ask of the cichlid lover.

Distribution

Endemic to Laguna Xiloá, Nicaragua. This is a crater lake that originated 6,500 years ago on the edge of a much larger lake, namely Lake Managua. Laguna Xiloá stands out for its (for crater lakes) high diversity. There was once a connection between the two waters that grafted Laguna Xiloá with a large number of life forms. In addition, Lake Xiloá has a heterogeneous bottom profile with a steep stony shore in the North and flat sandy beaches in the South. In between, there is room for different types of habitats. This combination of genetic and ecological factors can strongly stimulate speciation and has resulted in the emergence of new species of Midas cichlids in a few thousand years.

Some crater lakes are better studied than others. Laguna Xiloá and Laguna de Apoyo have now been properly inventoried, but we still know almost nothing about ten others. Nevertheless, the knowledge acquired has already led to new insights. Evolution is less random than always assumed. It seems that under comparable circumstances nature always comes up with the same (pre-programmed) answers. Examples of parallel evolution have been found in Laguna de Apoyo and Laguna Xiloá. Both lakes contain three types of Midas cichlids.

1. limnetic (open water) type
2. shallow benthic (bottom-facing) type
3. deep water benthic type

Evolution repeats itself and apparently produces the same phenotypic adaptations over and over again.

Habitat

Amphilophus xiloaensis is of type 3. and mainly inhabits the northeast side of the crater lake. So this is the steep basalt slope from the adjacent volcano, Apoyeque. Amphilophus xiloaensis can occur here up to a depth of 25 meters. She shares her habitat with ao. Parachromis dovii, Hypsophrys nicaraguensis and Neetroplus nematopus. Due to volcanic activity, the water temperature is high and fairly constant. Around 29 degrees Celsius. In some places of the crater lake the sulfur gas bubbles out of the bottom. In such locations, the water is downright hot. Mckaye (a Crater Lake specialist) expects to find up to 40 new species in the crater lakes of Nicaragua in the coming years.

Behavior

Midas cichlids are not territorial for most of the year. They school together in large groups of different ages and lead a nomadic life in the large pool. Only at the beginning of the breeding season, when pairs start to form, does the need for a territory arise.

Diet

Gastric examinations are unknown to us, but judging from the morphology of the mouthparts, the feeding pattern is largely similar to that of Amphilophus amarillo. Amphilophus xiloaensis also has millstone-like throat jaws that enable them to crack snail shells. The only difference is that Amphilophus xiloaensis has a few more teeth on the first gill arch. These are sort of feed sieves. This allows her to sift out finer food than Amphilophus amarillo. Perhaps Amphilophus xiloaensis is therefore less of a snail specialist than Amphilophus amarillo.

The Aquarium

When these fish first came to Europe (2001), they did not yet have a name. They were given one a year later, by Jay Jr. Stauffer, a professor of ichthyology who had extensive experience with Malawi cichlids. That first import was carried out by Willem Heijns. He had brought the fish along with many other cichlids from a trip through Nicaragua. These animals were housed in the Cichlidarium. This was a garage converted by Willem with very large aquariums. The adventures in Nicaragua and those of the Cichlidarium can be read in the NVC periodicals of that time. An important lesson learned then is that these animals require the necessary space. They are not overly aggressive and are also slightly smaller than Amphilophus amarillo (± 35 cm), but like to have a little free-range space.

Aquariums from 3 meters are eligible. In addition to the necessary swimming space and a substrate in which the animals can dig, shelters are also important. During the breeding season we see the mutual tolerance decreasing rapidly and fish of this size can seriously damage each other. A good filter installation speaks for itself. Following the natural conditions, we give these animals alkaline, hard water with a light addition of salt. The temperature in Laguna Xiloá is high and stable all year round. In the aquarium, we prefer not to keep these animals below 27 ℃. Although they are snail eaters by nature, they accept almost anything in the aquarium. Still, we have to be careful not to overfeed them. Like all other Amphilophus species, this species is predisposed to obesity.

Keeping them together with other Cichlids is quite possible, provided the necessary space is available. Because Laguna Xiloá is only a few hundred meters away from the much larger Lake Managua and because Laguna Xiloá once had an open connection with it, this crater lake also contains cichlids from Lake Managua. These include Neetroplus nematopus, Parachromis dovii, Parachromis managuensis, Cribroheros rostratus, Cribroheros longimanus, Amatitlania siquia and Hypsophrys nicaraguensis, Archocentrus centrarchus. Plenty of choice for a biotope-responsible combination. Keeping it together with other cichlid species from the Midas complex is, for obvious reasons, unwise.

Midas cichlids are of great importance to science because they offer the unique opportunity to study speciation processes in both similar and different conditions.

Breeding Amphilophus xiloaensis

The breeding season is at its peak in Laguna Xiloá in November / December. This is in sync with the other two Midas species of this lake. Amphilophus xiloaensis then breeds in real colonies between the basalt stones at an average depth of about 10 meters. The breeding grounds are then crowded.

The animals are really beautiful in breeding colours. The banding pattern is, perhaps due to the slightly whiter ground colour, even more contrasting than that of Amphilophus amarillo. Nothing changes with the “Gold morph”.

The sexes cannot be distinguished in colour and markings. Women may even develop a brow bump briefly. Men are, however, a bit taller in all cases.

Nests are large, up to 1,000 eggs. These hatch after three days and after another week the young swim free.

Video

Author

Rene Beerlink – NVC

Copyright images

AquariumGlaser.de

References

• Barluenga et al 2006. Sympatric speciation in Nicaraguan Crater Lake cichlid fish
• Dittmann M. at al. 2012. Depth-dependent abundance of Midas Cichlid fish in two Nicaraguan crater lakes
• Elmer K. et al. 2015. Local variation and parallel evolution. morphological and genetic diversity across a species complex of neotropical crater lake cichlid fische
• Elmer K. et all. 2009. Color assortative mating contributes to sympatric divergence of neotropical cichlid fish
• Heijns W. 2002. Ontmoetingen onder water. Cichlidae 28-5, blz 141 tm 148
• Heijns W. 2003. Ontmoetingen bij de voorruit, de duikervaring voorbij. Cichlidae 29-6, blz 165 tm 172
• Heijns W. 2005. Citroencichliden in alle maten en kleuren. Cichlidae 31-5, blz 105 tm 114
• McKaye K. et al. 2002. Behavioral, Morphological and Genetic Evidence of Divergence of the Midas Cichlid Species Complex in two Nicaraguan Crater Lakes
• McKaye K. and Barlow G. 1976. Competition between color morphs of the Midas cichlid. Cichlasoma citrinellum, in lake Jiloá
• Stauffer & McKaye. 2002. Descriptions of three New Species of Cichlid Fishes from Lake Xiloá, Nicaragua