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Finding dead shrimp daily in an established colony. Population capped out?


alkemist
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I have been finding dead adult shrimp daily in my tank, maybe 1-2 in the process of being eaten. My tank is established for about 9-10 months and everything was going great. The population exploded and appears to keep growing but the daily dead shrimp is worrying me. I probably have a minimum of 100 shrimp of all ages, including berried females in my fully planted 9 gallon tank. I have to admit, aside from doing water changes and dropping in food, I let the tank kind of do it's own thing. I did not observe the shrimp for some time, part of it due to the water being much darker (tannins and blocked light from plant mass) so I can't get a good viewing of the shrimp. I do not know how long the die off has been but I noticed it since last week.

The water parameters have been normal. Ammonia 0, nitrites 0, nitrates around 5, PH around 7.5, GH 6 and KH 6-7, TDS around 215. Temperature around 73F. I do a 10% water change bi-weekly with re-mineralized RODI. I lightly fertilize twice a week.

There should be plenty of biofilm and natural food in the tank, they are eating holes in my pennywort and dwarf lettuce. I always have 2 almond leaves in the tank and some snowflakes. I feed a little prepared food every other day, such as glasgarten shimp dinner, mineral junkie, bee pollen. I feed a little bacterAE and shrimp baby twice a week. When I do drop in food, they swarm it like mad, so it makes me think they are very hungry.

Some things I noticed, I removed a huge chunk of cladophora algae from my tank. I noticed a bunch of shrimp, including shrimplets feeding off it but it was choking out my java moss and blocking light to the bottom of the tank. I also noticed that some shrimp just stand around and seem to do nothing, which is worrisome. I recently had to lightly rescape the tank since the driftwood centerpiece became dislodged. I put in a small piece of eggshell plastic crate, after a good rinse, under the substrate to hold up the wood.

I am not sure if they are not getting enough food, the population is reaching it's natural cap (which is also due to lack of natural food), the older population is dying off (though it seems like shorter than average lifespan) or there is something wrong with my tank parameters.

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How is the moulting with your shrimps? Do you see old shells around?

With a KH of 6-7, it seems to be reaching the high side. That water parameter is considered 'hard water", so shrimps start to have trouble moulting.

Those shrimp just standing around that you notice, are probably in the process of moulting.

Getting the KH parameter down is something I would try first.

Edited by jayc
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Posted (edited)

I haven’t really seen much molts around lately. Though I did see one in the process of molting today and it did struggle a little bit.

I’m not sure what made my KH creep up again. I had higher KH, around this range when I set the tank up and I think it was the fluval fluorite that held onto some when I first flooded the tank with tap water. After switching to RODI, it went down over time.

I thought maybe the mineral junkie pellet leached a little into the water but it doesn’t really make sense since I’m sure the shrimp are devouring it quickly.

Do you have any ideas how I might get the KH down? As far as I know, my rocks should be safe and not leeching any minerals into the tank so I have no clue where that KH is coming from.

edit: checked my notes about previous GH/KH

Edited by alkemist
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KH creeping up can only be from fertilisers that are added, or from rocks.

As beneficial bacteria break down ammonia/nitrogen, the by product is slightly acidic water. This is a very simplified explanation. But the point is aquarium water will become acidic as the bacteria breakdown nitrogen. It is this acidic water that causes some rocks to increase KH or carbonates.

What rocks do you have in the tank?

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The KH is to high for sure and should be reduced, as JayC recommends. Best way to check the rocks is to put them (individually) into a container with pure RO water (which should be zero on all reading) and test the water after a week to see if it has stayed the same parameters. Water changes, slowly added is the only route I know of to reduce the KH!

Other than that, everything you are doing etc seems to be well informed! Are you convinced there really is any real problem (other than high KH) as shrimp only live 12-18 months anyway so it could just be natural life span with the high KH also contributing?

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19 hours ago, jayc said:

What rocks do you have in the tank?

I believe the rocks are banded jasper. Previously when I first set up the tank, I was worried about the rocks. I have done previous testing with them before. I don't have hydrochloric acid but I've done the vinegar and water soak test. I had a test rock in RODI for a month with no change in GH and KH. There were no reactions to vinegar. The rock was marketed for aquatic use but it doesn't always mean it's correct. Sometimes I do question it though. I previously moved some rocks higher out of the substrate to help fix the scape and there was a dividing line in the color of the rock. The portion originally above the substrate had darkened and the part that was previously buried in the substrate stayed it's original color.

The only other thing that comes to mind is that maybe I have been overmixing my re-mineralized water. I could have sworn that when I originally made the mix to 180 TDS in 1 gallon of water, it was 6 GH and 4 KH. I did some mix testing yesterday and at 160 TDS, it was 6 GH and 3/4 KH.

I did a 10% water change and replaced it with straight RODI water. It brought the KH down to 5/6 but GH also down to 5. I will do another 10% water change next week and probably add in mostly RODI and a little re-mineralized to keep calcium and magnesium content in the water for the shrimp.

 

14 hours ago, sdlTBfanUK said:

Are you convinced there really is any real problem (other than high KH) as shrimp only live 12-18 months anyway so it could just be natural life span with the high KH also contributing?

I think the KH rise could have been part of the issue. If I recall, I saw a shrimp laying around and twitching, like I've seen in a failed molt. The higher KH had totally skipped my mind and I went straight to thinking it was a food issue due to the ton of shrimp in the tank and light supplemental feeding. Though maybe it can be a contribution to possibly shortening their lifespan.

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11 hours ago, alkemist said:

I had a test rock in RODI for a month with no change in GH and KH. There were no reactions to vinegar.

It's good you tested the rocks.

There might be something else causing KH to rise.

What substrate do you use?

What filter and media do you have? Sponge air filter or External filter? I have seen cheap glass noodle filter media causing KH to rise when tested in RO water.

Reducing your fertiliser dosage also helps. If there is nothing else in the tank that is causing KH to rise, then it must be the ferts.

Using straight RO water for your water changes to reduce KH is a right path to take.

 

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17 minutes ago, jayc said:

What substrate do you use?

What filter and media do you have? Sponge air filter or External filter? I have seen cheap glass noodle filter media causing KH to rise when tested in RO water.

Reducing your fertiliser dosage also helps. If there is nothing else in the tank that is causing KH to rise, then it must be the ferts.

Using straight RO water for your water changes to reduce KH is a right path to take.

 

I use Fluval Flourite, which should be inert but should have some cation exchange capability.

I use a sponge filter but it's a design that has a small filter media chamber. I filled it with Fluval biomax which I use in my other tank with a canister filter.

I found another dying shrimp this morning. Seemed like a young adult male, might have been a failed molt but I can't tell for sure. I take it that KH reduction won't necessary see immediate effect since the shrimp have already developed their current shell? This would be something that takes time to fix for the shrimp?

Aside from the fertilizer, the only other thing I can think of is a contaminant got into the tank. I would think that affects all the shrimp and not seemingly select individuals.

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I checked my GH and KH today and it bounced right back up again.. 6 GH and 7 KH. So it makes me think something in the tank is leeching.

I recently tried to fix my wood stability with additional rock buried in the substrate with a few pieces of biomax. The spiderwood was superglued to a piece of flat rock originally for stability. About a week later, I wasn't satisfied and moved the wood too much and it separated from the rock it was mounted on. I had to dig in the substrate and remove what I thought everything I had previously buried. I added in the piece eggshell plastic crate under the wood to stabilize it. Maybe there is still a piece of or two of biomax buried. Only one Google search came up with biomax leeching temporarily but I don't know how accurate that is.

Maybe I'm being impatient, but I did another 10% water change with RODI today. GH and KH went back down. This mystery leeching is getting frustrating.

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Don't know if Biomax leeches carbonates. But only one way to know ... test it in RO water and see if it increases KH.

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Note that using just RO water will also drop the TDS and GH of the aquarium, as well as the KH!

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I have been able to get my tank down to around 170 TDS and 6 GH and 5 KH. I will continue to try to lower it a little more but it seems whatever has been making the KH go up has stopped. However I am still finding daily shrimp deaths. They look like juvenile/young adults now. I'm completely baffled. I am also seeing some molts in the tank. So some are making it and others are dying, assuming it's molt related.

Barring any diseases, pathogens or parasites (nothing new has been added to this tank), the only thing I can think of is that my tank population is naturally capping out. The strong are surviving and the weaker are dying. I know there is plenty of bio film in the tank but maybe what they are naturally foraging is not enough nutritional wise and the food I do add is not enough to go around. I picked up some Hikari crab cuisine which is made for inverts and should be calcium fortified in case it's molt related. I'm thinking maybe I need to feed them more quantity and more often? Am I even thinking this through correctly? I've been a bit stressed out with the daily shrimp deaths.

Edited by alkemist
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Correcting the water parameters now will only have an affect at the next moulting phase. So it's not going to be immediate.

It won't hurt feeding a bit more than usual if you suspect there is not enough food. So go ahead and try that.

 

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Hopefully the KH will gradually decrease with normal water changes/maintenance now, but as JayC says, it will take time to see any improvement with the shrimp as they need to molt first.

I use that hikari crab cuisine with my red cherry shrimp!

Its probably time to just settle down to a routine now and see how it goes, you may still lose a few in the next month, and keep a close eye on that KH.

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I thought things were starting to turn around. I did seem to loose a lot of older shrimp, I don't see as many around anymore but there are lots of younger generations coming up.

Then today I saw a fresh shrimp molt and what appeared to be a freshly molted shrimp, struggling to get away from everyone else in the corner of the tank. Other shrimp descended on the molt and I don't believe it was a female, but the other shrimps were harassing them. I go away for 5 minutes or so and I come back to see them feasting on a now dead shrimp. I'm not sure what's going on here and I think I had a hunch that freshly molted shrimp were being cannibalized. I started to sense this pattern for a little bit but didn't have any hard evidence. This was the closest that I've seen.

I'm not sure if the shrimp died naturally due to poor molting (seemed to be a good intact exoskeleton left behind) or if the other shrimps killed it when it was vulnerable. I think I saw a shrimp trying to pick at it while it was preparing to molt (this was right before I walked away).

I've been trying to get the water parameters under control and feed them a little more often. I'm trying to add mulberry leaves on a more regular basis. Along with natural bio film and algae, I believe there should be plenty of food to go around.

I don't know what's going on anymore 😔

Edited by alkemist
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Shrimps are scavengers and will eat other dead shrimps (or fish) but I dont think they would have killed another shrimp unless (possibly) it was already dying!

Keep at it! The juveniles moult more often as they are growing in size where as adults don't need to moult as often so the affects of your earlier problems are likely to have longer term problems with the older adult shrimps (thicker/harder shells). Hopefully though you have enough younger shrimps to restock given a bit of time?

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14 hours ago, sdlTBfanUK said:

Shrimps are scavengers and will eat other dead shrimps (or fish) but I dont think they would have killed another shrimp unless (possibly) it was already dying!

I was seeing this again today. Looked like a freshly molted shrimp and it was being torn apart. It was pale and didn't look like it had a hard shell. I've looked around the internet and I've seen people reporting such instances of cannibalistic neos. While it's not common, other people seem to have encountered this before. It maybe a lack of protein in their diet and they are looking for the next best source. I'm hoping the extra mulberry leaves and Hikari crab bites will help tone this back. Right now I drop in 3-4 crab bite pellets but I don't think that is enough to go around? I have no clue how much to feed without being considered over feeding.

I still have, or think I have, a healthy population, with lots of younger shrimp, from shrimplets to young adults. There are still some older adults around and some berried mamas but I no longer have my really big, massive shrimp I originally had. I'm going to guess that with the possibility of overcrowding and less access to quality food in general (with the population size), they aren't growing nearly as large. What still concerns me is that I do find shrimp that stand around and chill? They don't do a thing, just sit there, motionless. It's not in a specific corner, gathering or area, but just through the tank. I read some things online that shrimp do need to "sleep" but I don't know how true that is (there are not a lot of sources). I just remember that previously when I started the tank and the few months after, shrimp were constantly busy. 

Edit: today I did see at least 2 shrimp being torn apart. I don't know if they were dead or dying. The other shrimp were really savage and acting like they haven't eaten in days, fighting over the corpse. I saw another shrimp dying, it was all pale and looked like it might have struggled to molt. It tried to jump, like they do when molting but couldn't. I did not see a white ring of death or anything though. It was just pale, weak, laying there and twitching. I don't know what happened to it. I doubt it was able to molt but I didn't see a dead body where it was last seen. Losing 3+ shrimp a day seems to be a real big problem.

Water testing still showed 0 ammonia, 0 nitrites and about 5 nitrates. GH 5 and KH 5. GH is a little lower than I want but I'll try to bring it up on the next water change this Saturday. PH was the odd one. Originally when I measured, it was 7.5 PH but I very recently cleaned my PH meter and recalibrated. Now it's showing around 7.8 PH which seems kind of oddly high. Though I have no clue what would be causing that to rise. IIRC, it was 7.8 in the morning and was also 7.8 late afternoon.

Edited by alkemist
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@alkemist, try supplementing their food with frozen bloodworms. 

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If you add food and the shrimp swarm too it then up the dosage. In a tank with sufficient natural food, shrimps don't generally swarm commercially made foods/suppliments when they are added. Only so much biofilm can grow in a small tank and as shrimp spend most of their time eating, it won't get much time for the biofilm to grow back. It is difficult to know how much to feed and a lot of times overfeeding causes bigger problems, but if the shrimp make a bee-line for the food you add then it is likely they are having problems getting enough, or missing something in their diet! As you mention, protein may be deficient, and as the population grows obviously more food is required and sometimes people don't allow enough for that, ie they start with 10 shrimp and 6 months down the line have 70-80 shrimps so enough extra food needs to be supplimented to support that HUGE increase in population. As JayC states, bloodworm is high in protein, otherwise if that isn't obtainable, there are specific high protein commercial foods available. Put the food somewhere at the front so you can keep an eye on it and so uou can remove it if they don't go for it, or eat it all. I think you are already feeding baby shrimp food and bacter AE which is good and probably why the babies are doing so well!

Shrimp will 'rest' as any other creature, plus, as JayC said, they may be getting ready to moult, so I wouldn't worry too much if sometimes the odd shrimp is just 'chillin'. In a tank with no predators they are more likely to do that anywhere in the tank, whereas if they feel unsafe they would hide away!

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@jayc @sdlTBfanUK Thanks for all your help. Sorry for freaking out. I have this odd, irrational fear that I just end up losing all my shrimp randomly one day. Hopefully I can get this all back under control and have a happy tank again. I'm guessing that the massive population bloom over summer, KH creep and my own inexperience caused some long term issues. I suppose in a sense they are culling themselves... 

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I certainly know how devastating it is to lose a whole tank of shrimps, made worse as it was my favourite shrimps!

I think you will be fine going forward, though the occasional death will happen, but those should get less with time. Hopefully you will keep using this forum and let us have updates?

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15 hours ago, sdlTBfanUK said:

Hopefully you will keep using this forum and let us have updates?

I will most definitely keep using this forum. I'll let things work out for a bit and post back with hopefully good results.

Seems like even after the past week of upping the food quantity in the tank, the natives are less restless and seem happier and fuller. They also seem much redder than previously. So I think this is going in the right direction.

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