ARK - Arizona Rivulin Keepers

Eurasian Killifish

The following was translated from the website of the German Killifish Association (DKG) study (or work) group: AG Eurasische Killis . It was translated into English by the computer program Babel Fish and then edited by Allan Semeit.

The study group Eurasi Killis deals with the maintenance and breeding of egg-laying tooth carps of the kinds Aphanius (now Lebias) and Valencia. Special attention is given to those species where, due to their rarity in the natural habitat (i.e. - Aphanius apodus) a species preservation effort is being made. Also those species that are suitable for keeping in garden ponds have been found interesting to our group.

  • Aphanius anatoliae
  • Aphanius anatoliae splendens
  • Aphanius anatoliae sureyanus
  • Aphanius anatoliae transgrediens
  • Aphanius apodus
  • Aphanius asquamatus
  • Aphanius danfordii
  • Aphanius dispar
  • Aphanius dispar richardsoni
  • Aphanius fasciatus
  • Aphanius ginaonis
  • Aphanius iberus
  • Aphanius mento
  • Aphanius sirhani
  • Aphanius sophiae
  • Aphanius vladykovi
  • Valencia hispanica
  • Valencia letourneuxi

    Distribution and condition of the native biotopes

    The distribution of Aphanius species extends over coastal waters of the entire Mediterranean, the Red Sea and Persian Gulf, with the exception of the Balearic Islands. In the North African and Asiatic distribution area, these killifish are also found in the interior. They inhabit all types of water: fresh-, brackish-, and seawater. In some areas the fresh water derives a high degree of hardness due to very alkaline soils. Some habitats contain water that is more saline than the ocean or have a proportion of sulfates and magnesium concentrations. All native waters of the Aphanius group can be characterized as flat, or possessing a flat bank, and are exposed to strong sun light. The fish tend in live in the shallow water, preferring to stay among aquatic plants or in algae growths. Young fish tend to form large schools.

    Fish of the genus Valencia are found in east Spain as well as in the southwest of the Balkan Peninsula from southern Albania to the Peloponnese. They prefer calm portions of flowing freshwater, especially those areas that are completely shaded by trees or other vegetation.

    Maintenance and Breeding in the Aquarium

    All Killifish from the generas Aphanius and Valencia are lively and enjoy swimming. They should be maintained in larger tanks than most killifish. They like thick plant growths where they can dart into and hide, which additionally serve as spawning sites and offer some protection to the very young fish. When you consider that these fish are often found in schools or groups, you will find that they do better when kept in larger numbers. The presence of other members of their species offers the security of the group. Male aggression can be reduced or avoided by this. This is particularly important in the maintenance of Aphanius mento and Aphanius iberus. The disputes that determine the dominance rankings are generally kept harmless when there are large numbers of fish.

    For maintenance and breeding, moderate to hard freshwater is suitable for most species. For water with a total hardness less than 10 dGH, it is recommended that sea salt be added (approximately one teaspoon per 10 liters). Some species that inhabit brackish or marine biotopes (e.g. - Aphanius fasciatus) cannot be maintained without the addition of sea salt.

    These fish are relatively tolerant of temperatures. During the warmer months 20 - 25 C is fine. Higher temperatures do not harm the fish. They become more active, however, they also age substantially faster.

    During the winter months the temperature should be slowly lowered. This allows the fish their natural way of life to regenerate. This is not easily implemented in today's modern housing conditions. Options include maintaining aquariums in unheated dwellings, cellars or winter gardens, so that the water cools in the winter months to temperatures under 20 C. Species in the northern part of the distribution range experience cold winters (Continental climate) and inhabit waters to drop to temperatures below 15 C and they still spawn! Clearly fewer eggs are produced and survive, but life continues nevertheless.

    Weekly partial water changes are recommended. In particular, fish of the genus Valencia often originate from flowing waters and do not tolerate poor water quality. They show this through clamped fin and illnesses, which lead inevitably to the loss of the fish. The frequency of water changes can be reduced by a decreasing the fish population, providing dense stands of plants, and feeding live foods.

    Eurasian killifish are quite undemanding about their food. As long as the food is a size that can be consumed, all species will eat live or frozen fish foods. It has been reported that they also eat flake foods. When kept at higher temperatures, these fish require larger quantities of food. This is particularly important for females preparing to spawn.

    In nature, the spawning season begins in the spring and stops during the summer. During these times, there will be periods of large and small spawning groups. When kept under aquarium conditions (> 15C) these species breed during the entire year. During these egg-laying sessions, the breeders will prefer to deposit their eggs on fine-leafed plants (thread algae, Java Moss, or yarn mops), but eggs may be laid on sponge filters or in the aquarium gravel or substrate. Depending upon temperature, the eggs take 8 to 20 days to develop. Upon hatching the fry take about two days to consume their yolk sac. At that point they become free swimming and will consume baby brine shrimp. With plentiful quantities of food, the fry of Aphanius species grow rapidly. After approximately a half year the fish reach sexual maturity. In comparison, fish in the genus Valencia grow quite slowly and need approximately one year to reach sexual maturity.

    Maintenance and Breeding in the Outdoors

    Eurasian killies can be kept outdoors. They can be housed in garden ponds or in aquariums on balconies etc.. These natural living conditions provide the advantage day and night temperature fluctuations, exposure to the direct sun, and the opportunity to forage for insects. These circumstances provide the conditions for optimal growth for young fish. Also when maintaining killifish in an outdoor setting, you can observe the natural behavior of the fish.

    When maintaining a pond, it is quite common for an algae pad to form. This pad floats on the surface and the algae threads often serve as a spawning substrate. Eggs laid in the pad receive an optimal amount of oxygen and are warmed up by their position at the water surface by the sun. This enables the eggs to develop under ideal conditions. After hatching, the algae pads offer protection from predation by the older fish and provide a food source during the first days of life.

    The open nature of outdoor rearing also has it drawbacks and dangers. Besides providing food sources for the killies, predators are attracted to your pond or aquarium. Insect larvae, such as Aeschna grandis and Libellula depressa, appear frequently and can reduce the stock of young fish in your pond. Even worse, the larvae of the beetle Dytiscus marginalis can endangered your entire fish population. It is strongly recommended that you regularly check your outdoor containers for these unwanted for co-inhabitants. Remove them when found.

    Another circumstance that can endanger your killifish is the degradation of the water quality. This occurs most frequently from summer rains. The precipitation (acid rain) can include minerals that reduce pH value to such an extent that the fish in the pond cannot survive. You may have to return your killies to an indoor aquarium. Therefore hardness and pH value should be checked regularly and if necessary the water can be changed.

    In areas that experience mild winters, some killies can be left outdoors year round. In these situations, leaves should be removed from the water in order to avoid decomposition. Some leaves will strongly discolor and acidify the water. When ice covers the water surface, the decomposition can also reduce oxygen from the water and that may cause the fish to die. Again, it is Important to monitor the water quality. The use of foil tents or covers, placed over the pond, improves the micro-climate and prevents precipitation from entering your outdoor container. Killies that are wintered this way usually breed well in the coming spring and this provides a good basis for further fish generations.