How do shrimp reproduce?
The principle of shrimp selection to maintain a pure line.
If you have a certain species of shrimp and want to maintain the best quality criteria for this species, you need to select breeding stock that meets specific requirements. To do this, you should have a main (general) aquarium and breeding aquariums where the parameters (pH, GH, KH, conductivity, temperature) are exactly the same as in the main aquarium. If you wish to keep shrimp of different grades, you must have identical aquariums for each grade.
1) Place breeders that meet the criteria into two small dedicated aquariums. Keep the best males and the best females separately.
2) Place less attractive individuals that do not meet certain criteria into the general aquarium.
3) Observe the newborn shrimplets, and before they reach sexual maturity, transfer all the most attractive ones and those that best meet the standards into a separate breeding aquarium, while putting the rest into the general aquarium.
4) Continue this process through many generations and, if possible, occasionally introduce fresh blood to prevent degeneration.
5) Remember the basic rules: good gene pool, good food, frequent water changes, ruthless culling, and as a result, you will become the happy owner of a beautiful pure shrimp line.
Why does shrimp degeneration occur?
Knowledge about the results and consequences of shrimp mating from a genetic standpoint will help the shrimp keeper take care in advance of maintaining a quality stock of shrimp and avoid species degeneration. Most often, shrimp are bought in one place, and they are descendants of a single shrimp family. That is, they are relatives and share a common genome (a set of genes from ancestors). Plus, there could have been several female parents from which these offspring were taken, and each of them acquired certain traits during her life that were passed on to the offspring via new genes. In other words, there is gene diversity, but a lot is shared.
Crossing representatives of the same genus or family is called incest. If new shrimp are not added to the initially purchased stock over time, the uniformity and poverty of the gene pool will soon lead to the deterioration of the offspring line and the degeneration of quality representatives of this species. Without rigorous selection for coloration brightness, over a dozen generations (about a year to a year and a half), they lose their color. Not all at once, the transition occurs through a gradual decrease in pigmentation intensity.
That is, in the offspring of still bright shrimp, the majority first become dull, then their offspring become transparent with red-pink speckles, and after that, their children become completely transparent with characteristic black dashes on the dorsal side of the abdomen. Introducing fresh blood, i.e., adding genetic diversity to the shrimp herd, brings new interesting manifestations in the offspring: the appearance of new color variations, color saturation, and strengthening of the shrimp’s immune system. In addition, by adding “fresh blood,” you can regulate the ratio of males and females in your aquarium.
No matter how high the quality of the breed line is, parents will still produce weakly colored offspring. The offspring of a mixed stock will still contain substandard specimens, so if you want to keep select shrimp, you will need to cull the offspring. Discolored individuals (if they are *Neocaridina*) or those that have lost color opacity (if they are crystal shrimp) are removed from the breeding tank. With a sufficient number of breeders, selection should be made based on the offspring, culling not only the descendants but also the parents.
The maximum allowable percentage of substandard offspring that triggers parental culling should be within 30%. That is, if a pair of shrimp produces less than 30% weakly colored offspring, only the offspring that do not meet the required characteristics are culled, while the rest of the brood and the parents are kept for further breeding. If the proportion of culls in the offspring exceeds 30%, both the parents and all offspring are culled.
It is pointless to add a couple of brightly colored shrimp to a full aquarium of semi-transparent ones — the population will quickly “genetically absorb” them, and no color enhancement will occur. It is easier to catch out excess transparent shrimp using a trap from time to time and then introduce bright ones. It is worth noting that the discoloration of crystal shrimp can be caused by deteriorating water parameters or shrimp aging. In such cases, the cause is easily identified if all or most of the shrimp have lost color. Culling is performed when individual specimens lose color opacity. The addition of fresh blood and the culling of substandard individuals are components of inbreeding. Inbreeding is the crossing of the highest quality specimens of aquarium shrimp of the same species, but from different families.
Subsequently, to breed particularly high-quality and valuable specimens, linebreeding is performed, meaning the crossing of the highest quality representatives of a single related line (one family) in a separate aquarium. The quality of Red Crystal and Black Crystal shrimp is improved by crossbreeding — crossing closely related representatives of these two species. Linebreeding helps to subsequently produce high-class shrimp. Crossbreeding also contributes to obtaining new selective forms when crossing closely related *Caridina*, such as tiger shrimp and bumblebee shrimp, or tiger shrimp and Taiwan bees. Then, to fix the obtained types, representatives of different bloodlines with similar traits are required. For example, yellow, green, black, and red *Neocaridina* appeared this way. This is how Panda and King Kong shrimp, as well as many other rare-colored *Caridina*, were bred.
Macrobrachium nipponense, Macrobrachium assamense.
