One of the biggest misunderstandings in shrimp keeping is which shrimp are compatible. If you look at the genus (the first word) in the scientific name of a particular shrimp, this will let you which shrimp can breed together (should not be placed in same tank) and which can’t (acceptable to be put together). For example, the cherry red shrimp’s scientific name is Neocaridina heteropoda and the blue pearl shrimp’s species is Neocaridina zhangjiajiensis. These two shrimp are completely different species, but they can and will breed together to produce an ugly looking offspring. Therefore, they should not be kept together in the same aquarium.
On the other hand, the crystal red shrimp and crystal black shrimp both have the same exact species name – Caridina cantonensis. Most people think that because of this you should not keep crystal red shrimp (CRS) with crystal black shrimp (CBS), but this is no different than a human with black hair and a human with red hair having a baby. They are the same species, just a different color. This means that the colors of shrimp can be determined using a Punnett square.
A Punnett square is a way of predicting offspring from certain genes. The black color in crystal black shrimp is the dominant gene and the red color is recessive. This means that if a red shrimp and black shrimp breed, the black color will be visible, but the offspring will carry the red gene with them. So if the offspring of a black and red shrimp breeds with a red-colored shrimp, some offspring will be black and some will be red…
If you calculate all of the possible combinations of offspring, you will find that the odds of black to red is 3:13 or 81% black and 19% red. There’s nothing wrong with these odds, but if you start with 5 black shrimp and 5 red shrimp, you will have mostly black in a few months and the red shrimp will be a minority.
I’m in the process of starting a shrimp-only tank right now and I’m still trying to decide which kind of shrimp I want to get. Both crystal black and crystal red shrimp are very fascinating, but at about $5 each, they are very expensive to get a good colony going. I’m still debating between getting cherry red shrimp with another species that get along and do not breed with cherries or starting a pure crystal red shrimp tank. After calculating out the odds of black v.s. red, I would only want to introduce crystal red shrimp to my tank. If you have either (or any) species of shrimp, let me know what you prefer in the comments below.