A 20-gallon tank is a good size if you want to keep Red Cherry Shrimps as pets. So, how many of these inverts should you add to your tank? You can find out in this article from Aquarium Blueprints.
Bioload
The biggest factor you should consider, when it comes to how much RCS you should put into a 20-gallon tank, is the bioload.
For the uniformed, this term refers to the organic wastes being produced by the shrimps. Excrement will add ammonia to your tank water, which is extremely deadly to all the inhabitants in the aquarium.
To prevent ammonia spikes, you need to build up the beneficial bacteria in your tank, which is done by the cycling process. Once your tank has been fully cycled, the bacteria will automatically convert ammonia to nitrite, which is another toxic compound. Thankfully, another bacteria type will convert nitrite to nitrate.
While nitrates aren’t as toxic, it could cause health issues to your Cherries if you exposed them to a concentration of more than 20 ppm for long periods of time. To get rid of nitrates, you can do water changes or add a specialized filter media like Seachem Matrix.
The good news is that the Neocaridina species that the Red Cherry Shrimp belongs to produce very little organic wastes. Therefore, you can easily fit several hundreds of these creatures in a 20-gallon tank without any major problems as long as you keep nitrates to below 20 mm as well as ammonia and nitrites to 0 ppm.
Spacing
Another factor you need to pay attention to is spacing as your shrimps will need room to move and swim around the tank.
This shouldn’t be a problem at all as Red Cherry Shrimps have a narrow body and will grow no more than around an inch in length. We have well over 100 of these creatures in our 20-gallon tank and they have more than enough room to easily move and swim around.
Breeding
If you have male and females in your starter colony, then they will likely end up breeding. Therefore, you may want to take into account the future generations when it comes to picking the right number of shrimps to add to your tank.
When it comes to breeding, we suggest diversifying the gene pool as much as possible to prevent inbreeding, which can end up causing health issues for future generations. One of the ways of doing so is to start out with a healthy number and then periodically adding a new shrimp or two into the mix down the line.
Even under the most optimal conditions, most Neocaridinas will live for no more than a year or two. Therefore, we suggest that you add males and females so that you can keep your colony going for a lifetime.
When we first set up our 20-gallon fish tank, we ended up adding around 20 cherry shrimps. Despite our best efforts, the initial batch end up dwindling down in numbers as we struggle to keep most of them alive. Furthermore, we weren’t able to get our shrimps to breed.
It wasn’t until we added another batch of 20 shrimps from a different source that we finally saw some success. Once we managed to keep our pets alive and they started to readily breed, the population started to increase.
Over Population
Once we managed to grow our colony, we ended up having at least 100 Red Cherry Shrimps in our 20-gallon fish tank.
While that number could be even higher, we don’t feed our colony excessively. As a result, less babies are being produced due to the lack of extra food.
In an overpopulated tank, ammonia, nitrite and nitrate spikes are more likely to occur. So, if you feel that your colony is growing too rapidly, you can try feeding less.
Summary
To recap, we recommend that you start out with around 20 shrimps for a 20-gallon tank based on our experience. That amount should provide plenty of gene diversity when it comes to breeding. Not to mention that it should also account for any unforeseen death of males and females from the starter colony.
If you see that population in your aquarium is decreasing instead of increasing after several months, then you can try adding another batch of 20 shrimps, preferably from a different source.
Once your colony starts to grow, the shrimps should help fill out your 20-gallon tank. As long as you don’t overfeed them, they should be able to self-regulate when it comes to population control.