# Cherry shrimp life span???



## virgo888

What is the life span of a cherry shrimp? I had 80+ and I only see a few now..


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## JohnPaul

From my experience, 1-2 years is a typical lifespan. If you had 80 and are down to only a few, then something is probably wrong. Cherries breed like crazy and typically keep breeding like crazy unless they are overpopulated or else the tank conditions are no longer to their liking. How big is the tank, what else is in there, and what are your water parameters? What has your feeding regime been with them? Is the tank planted, how much light, do you fertilize, etc?


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## virgo888

i know they breed like crazy in my other tank I had hundreds until i put a pea puffer in there. he ate them all. lol. current tank is 20g, fully planted, co2, ph 6.9, nitrate = ~25, po = ~4, feed using algae wafers/pellets(same stuff i have been using), 7 hrs light, CSM+B and KNO3 - every other day, CaSO4 and MgSO4 - weekly. water change 4-6 weeks but top off as needed.


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## JohnPaul

Well you forgot to mention initially you had a puffer in the tank, no wonder your population is disappearing lol. If you yank the fish out then you should see the population increase again. Though your nitrates are on the high side (for a shrimp tank) and that combined with the amount you fertilize is probably going to inhibit the shrimp somewhat. In my own experience keeping dwarf shrimp of the _Neocaridina_ genus (RCS, Yellows, Blue Pearls, Snowballs) is that somewhere in the 20-30 ppm nitrate levels is where you start seeing a reduction in reproduction. I've never attempted to measure it scientifically, this is just my "gut sense" from having had many shrimp tanks over the years.

The other thing to keep in mind is to watch your TDS. In a tank that is heavily planted, with heavy ferts, and water changes only once every 4-6 weeks (really?), my worry would be that even if the normally-measured water parameters are "fine," your TDS are going to be increasing. And one of the theories among shrimpkeepers as to why shrimp populations suddenly crash in a tank where seemingly the water parameters are normal is due to this TDS creep.


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## Gordonrichards

Longer the photo period, the more stable the tank!


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## virgo888

What does TDS stand for?


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## JohnPaul

*TDS = total dissolved solids*

It is a value that is related to hardness (general hardness, or GH) but where GH measures only the amount of Ca+ and Mg+ ions, TDS measures all of the "dissolved stuff" in the water. (Or more accurately, all of the non-organic dissolved stuff.) For example, by dosing KNO3 regularly you are dumping large amounts of potassium into the water. The nitrate from the KNO3 gets used up by the plants, but the potassium...not so much. Plants use a little potassium for sure, but plants use a ton more nitrate than they do potassium, yet when you dose with KNO3 you are putting equal amounts of each into the water. The net result over time is your potassium levels build up higher & higher. And it's the same thing with the CaSO4 and the MgSO4, you are dumping sulfate into the water yet plants use (essentially) zero sulfate. So over time, sulfate levels climb higher & higher. There's continually more "stuff" in the water. At low levels this stuff isn't harmful, but without water changes that are regular enough, eventually it starts building up to the point where it could be harmful. Topping off tanks, rather than doing true water changes, also adds more TDS every time you do it.

Measuring TDS is a good way to kind of keep tabs on whether you are doing water changes frequently enough. In my case, the TDS in my tap water (which is what I use in all my tanks) is around 180-190 ppm. In tanks where my regular maintenance is good, TDS levels are typically around 200-225 ppm. In tanks where I have gotten lazy about water changes, my TDS can climb to 300 ppm or even higher. (Note that if you have a substrate that softens water like ADA Amazonia, that is going to impact your measurements. Same if you have a substrate that hardens water, like crushed coral or aragonite. But if you are using an inert substrate and you don't have any peat or tons of driftwood or anything like that, then in general comparing the TDS of the water you are putting into the tank versus the TDS of the old water in your tanks is a pretty good measurement of whether or not stuff is building up.) I've heard of cases where people neglected tanks and did like one water change every 3 months, and then two years later their TDS levels something ridiculous like 800 ppm. According to the EPA, TDS of 500 ppm is the maximum level that is considered safe for human consumption. However, once TDS levels start hitting in the 300-400 ppm range, most people would complain that the water "tastes funny," i.e. tastes more like well-water than tap water. (Obviously that's a subjective opinion so it could vary from one person to another.)

Another good reason to measure TDS is because if TDS levels are rising, than it is also very likely (in a planted tank) that the level of dissolved organic compounds (DOC's) are rising as well. These result mostly from the breakdown of decaying plant leaves. Unfortunately there is no easy way to measure DOC's in an aquarium setting. But if they build up high enough, it is likely they can negatively impact shrimps or other creatures as well.

You can buy cheap TDS meters on Amazon.com for $15-20. (Just do a search for "TDS meter".) They might not be as accurate as a $50 or $100 meter but they are accurate within +/- 2% or so which is more than good enough to be able to tell you whether or not you need to be changing water more often.


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## virgo888

Thanks. That makes sense.


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## Gordonrichards

+1


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