The cardinal shrimp (Caridina dennerli) belongs to the group of dwarf shrimp. This 2 cm high shrimp species enchants with its intensive red colouring. The colour tone can vary from lighter red to darker red (wine red). As a contrast to the body colour, the white shears stand out. There are numerous white dots on their narrow body, some of which can turn bluish.
The legs are adapted to the body colour. The overall appearance of the cardinal shrimp is majestic and elegant. It is not possible to differentiate between the sexes visually. Males and females differ neither in size nor in colouring. The small physical difference in older females (more pronounced belly pockets) is not particularly noticeable. The life expectancy of cardinal shrimp is two years.
Cardinal prawns are sociable. They feel most comfortable in a group of at least 10 animals. It is more difficult to create the ideal habitat. This shrimp species comes from Lake Matano on Sulawesi. The special living conditions of this Indonesian water must be achieved in the aquarium. Due to the body size of the animals, they can already be kept in a 20 litre tank. The water temperature should be between 27 °C and 32 °C. The water must not contain any residues of heavy metals or other pollutants. The use of demineralised water is recommended. By adding specially adapted mineral salts for the cardinal shrimp, an optimal water quality is achieved.
The pH value should be in the range of 7.9 to 8.5 and the total hardness should be 10 °dGH. Rainwater filtered with activated carbon can also be a solution. Once a week the water in the aquarium must be renewed at 50%. An absolute sterility must be achieved. Fine sand or gravel for the aquarium floor is ideal for the runny shrimp. There must be sufficient possibilities for hiding and protection. This is achieved by roots, branches and various stony structures. A light current makes the environment perfect. A variety of plants is not necessary. On the one hand, many green plants do not tolerate the water climate and on the other hand there are hardly any underwater plants in their original habitat. By leaves and moss the aquarium landscape can be loosened up a bit.
The cardinal shrimps are so-called rearing eaters. The decoration (stones, wood) should allow algae growth. These are diligently grazed by the shrimps. The easiest way to feed them is to regularly renew this decoration with algae-covered stones and roots. The algae growth on the aquarium panes can also be used by the shrimp to find food. The existing moss and leaves also serve as a food source. The stony or sandy bottom is regularly searched for deposits and grazed. Of course you can also feed a special shrimp food, spirulina powder or plankton tablets (crushed). This additional feeding should be done sparingly.
The breeding of cardinal shrimps is easier for two reasons. Firstly, this shrimp species produces fully developed juveniles and secondly, breeding is possible within the “familiar” tank. This means that the laborious process of moving the young animals to a brackish water tank is no longer necessary. For successful breeding, the quality of the water is of paramount importance. The better the conditions of the original home are imitated, the more positive the offspring will be. Every six weeks the female produces eggs. There are 15 to 20 of them. After moulting she presses the eggs out. During the “mating swim” the eggs are fertilized by the male. During the gestation period of three to four weeks, the female cardinal shrimp keeps the eggs under her abdomen.
At the end of the development phase, the small finished cardinal shrimp hatch. The freshly hatched animals have a light red colour that darkens within a few days. The offspring are independent from birth and do not depend on the care of the mother. Until they reach adulthood, the little ones will shed their skin a few times. This procedure is necessary because the carapace does not grow with the baby. After hatching the young, the mother can produce eggs for reproduction again. A balanced diet supports the growth of the “baby shrimp”.
The peaceful and shy cardinal shrimps live with their own species without any problems. Keeping them in larger groups is recommended. Experts suggest a socialization with other dwarf shrimp. Above all, these specimens should also come from the Sulawesi area and be accustomed to the water conditions. Water snails (Tylomelania) are also suitable as roommates. There are different opinions about fish. Some of the aquarists are against the socialization with fish, the others think small ornamental fish are suitable. Here you should get extensive advice from a serious breeder.