Two months ago I wrote an app for myself to keep track of my new hobby Neocaridina Shrimpkeeping. It was only 2 weeks before that I started the hobby before I recognized that a handy application to keep track of my shrimp’s water parameters, treatments and care with curated, accurate information would be very useful. You can read about it more and download the complete app for free (for Windows) from here.
To see some of early-stage shrimp collection photos, see this post. To see all shrimp-related blog posts, click here.
In this post, I am sharing a new program that projects what the shrimp population will be after x number of years. For example, I wanted to know if I start with 20 neocaridina shrimp, considering that they live 1-3 years, with relatively high mortality rate, but also they can breed often under perfect conditions, how many shrimp will I have after a year, or after 2 years, or 5 years? And what if I change the mortality rate, reproduction rate, and/or start with a larger starting population…how will that change the final population after that many years? My app will find the answer for us and also draw a line chart showing population year over year through that duration.
It’s a smaller application that solves that and you can execute it right on this page from your browser. But first, it’ll be helpful to give you quick overview.
It will ask for the required parameters such as the initial population of the shrimp (how big is your stock). Then it’ll ask for the average mortality rate per year. It is not unusual to have 10% to 50% mortality of neo shrimp every year! They are quite sensitive to water parameters as well as prone to issues with molting (when they shed their exoskeleton regularly and grow a new one), etc. So for example: if about 15% of the whole shrimp population die every year, you will enter: 15 (don’t include any percentage sign or fractions or decimals; the program will convert them as needed). You will only enter whole numbers for all inputs.
Then it’ll ask you to enter average reproduction rate per year for each female. Neo shrimp can breed quite often (every 3-6 months) and each time they can have 20 or more eggs. Although not all of the eggs or larva may survive. For example if you notice that each of your female shrimp has 40 new shrimp births per year, then enter 40 (whole number only). Remember both the mortality and reproduction figures are yearly numbers, not monthly! So, if you only have data for 6 months durations, just enter double that number to make it yearly.
Finally, it’ll ask you for how many years you want to project. For example, if you want to know how many you’ll have next year, you will enter 2 (not 1, because the program’s first year is the initial year). Similarly you can project for longer duration. Again, this is in years, and whole numbers only. The app does not do input error handling for brevity so it will not give error messages or fail gracefully…if that happens, you’ll just restart the program by clicking on Stop and then Run again.
Once your inputs are entered, you’ll get a table of exact number of population change year by year. Then you’ll also get a line chart as examples below.
As you can see with smaller colony and shorter duration, the population goes exponentially, however it slows down (they self-control too) as the population increases and you’re looking at a long duration due to higher mortality but we still get net increase.
Now, you’re ready to run it! Go ahead, give it a whirl! Just click the 
Run button in the widget below.
Note that this is just a simulation; the actual longevity, reproduction and mortality rates depend on numerous factors such as their tank conditions (pH, GH, KH, TDS, NO2, NO3, NH3, temperature, toxins in your water, etc.), presence of other predators, proper and natural maintenance, diseases, and even their breeds and specific breeders. Nevertheless, it does a good job of predicting the population given realistic inputs. I’d like to use 15% as mortality rate, and 30 as reproduction rate, and then project from there for x number of years to get a sense of when I can give away/sell some, when my tank will have too many etc. General recommendation is, for example, 5 neo shrimp per gallon…so you can plan your capacity too using the app. Hope you found this interesting and helpful.
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