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Swimming in Circles like a Shrimp Merry-Go-Round?


gtippitt

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Do any of you notice that your Neo's swim in circles around their tank?  The colony of Neo's I bought have tripled their numbers in the past few weeks, from about 60 to 200+, with lots of new babies. Their tank is a 20 gallon long that is about 70*30*30cm.  The water current in the tank is a very gentle flow from the top at one end to the bottom at the opposite end.  Whenever I sit and watch them, about half are always swimming clockwise around the tank keeping next to the sides.  They are semi-evenly spaced from top to bottom, with a few more at medium depth than at the top and bottom.  They are also evenly spaced out in the parade, with equal numbers going left to right at the rear of the tank as there are going right to left at the front of the tank.  Occasionally a single shrimp will swim a short distance in the opposite direction to the parade, but these are normally just swimming a short distance from one plant to another to graze.  The half that are not on parade will be either grazing on plants, eating at the large mussel shell where I drop their pellets, or hiding away in some hiding place.  The size participants in the parade also seem normally distributed from the largest to tiny babies.  As the parade adds and loses members over time, they remind me of line changes during an ice hockey match.  Some leave parade to eat or rest, while others join in swimming along.  The larger shrimp swim faster than the babies, but they otherwise keep a fairly orderly circle going about the same speed.  It's not a breeding behavior, as the the parade consists of males and females with eggs at varying degrees of development.

If anyone has noticed their shrimp swimming like this, I would love to hear about it.  Especially since many of you are in the southern hemisphere, I wondered if they swim the other direction perhaps.  I live in the US.  I've watched and my shrimp always go clockwise whether the weather is a clear day with high atmospheric pressure or raining with low pressure. 

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You have well trained shrimp there.

Can't say I have seen shrimp in my tank do that.

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Neither in any of my shrimp tanks have I seen anything of the sort. Except when females are molting then they go nuts all over the place. Would be great to see though could you upload a video on YouTube or something and share the link.


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Below is a video clip I uploaded to YouTube to show what I tried to describe. It is impossible to see the small babies that are also swimming along with the adults. When I first got them 3 weeks ago, they spent much of their day hiding, but began being more active after a few days. 

I can't say exactly when this circling behavior began.  I first noticed it a week ago.  The number that take part varies during the day.  Sometimes there are only a dozen or so, but at other times more than 100 of them will be swimming around in their parade.  During the past week that I've been specifically looking for this behavior, I have not ever look in on them without seeing a few doing their circumnavigation of their world.  I added the calliope music afterwards, so it is not that they think the circus has come to town. ;-) 

Although he was eating shrimp chow when I was recording this video and can't be seen, there is one male in the colony that I call easily tell apart from all the others due to him being blue and green, while the others are red or a wild looking brown.  Yesterday I watched him make at least 4 complete trips around the tank before he realized that there were new pellets to eat in their feed bowl.  I don't know how long he had been swimming before I sat down to watch them, but the distance I watched him swim was the equivalent of me swimming 500 meters at top speed without slowing down, which I cannot do.

 

 

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I wonder if the shrimp would "settle" more if they had more thick plant cover like java moss or even some long eloda or similar tall growing bushy plant.

I don't know if you hold with lay lines but scientists have discovered that cows grazing will almost always face in the one direction (north- south) and if they are near high energy power lines which interfere with magnetic fields the cows will be more hickilde-picklede (in other words all over the place). People have also noticed health issues and strange behaviours in fish that had a lot of electrical currents near their tanks, possibly caused by electrical wires that are hidden in the walls. So I wonder if something similar is happening with your shrimp, some sort of electrical/ magnetic field that is disturbing the shrimp.

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@Baccus

Nice catch on the magnetic lines!  It was one of those things that I have read, thought was interesting, and then it got filed away with tivia somewhere in my mind. Not only do grazing animals display that behaviour, but dogs frequently face along magnetic lines when they defecate, unless the terrain is un-level so it is easier to stand facing another direction.  My back yard is flat, and my two female dogs also always face north when they squat to urinate. The front of this tank faces due north, with the longest sides of the rectangle going east and west.

This tank is a fairly new setup.  I have several sprigs of Jungle Vallisneria (aka eelgrass) which are still small and haven't yet grown out very tall at that end of the tank.  The other end has a large sponge pre-filter that is about 2/3 the size of soccer ball, which the shrimp love to crawl all over and under.  I like using a large sponge pre-filter even though they're a bit ugly, because they keep the bio media in the main filter free of debris, add extra bio-media capacity, and diffuse the pump intake to protect small critters.  

Since the permanent plants are still small, I also have a large bunch of Pothos vine with a huge root cluster that fills up about 1/4 of the tank.  It works wonders to suck up nitrates as well as ammonia in new tanks when the bio media hasn't finished getting populated with microbes.  The shrimp spend much of their feeding time grazing on the bio-film of microbes on the Pothos roots.  The vine also works wondrously to hoover up excess nitrates in a tank whenever I find the levels have risen in a tank or algae becomes a problem.  The Pothos grows so fast that it can starve the aquatic plants in the tank of nutrients if left in a tank all the time, so whenever it's not need in one of my tanks, it has a home of its own in a large, water-filled pot with some fertilizer.

I don't have any major power lines near my house, but in the same room with my fish tanks, I do have a large computing cluster that draw about 2500 watts when running at full capacity.  It's a case-less thing I built of 3 motherboards, 6 graphics cards, 'egg-crate' lighting diffusers, and zip ties, without any metal shielding.  With 75 CPU cores plus the GPUs, it creates enough RFI that I have trouble with WiFi and Bluetooth in that room when it's running fully busy.  It's only been running a few jobs lately, but the RFI might still be making the shrimp OCD.  I'll try powering it down for a few days to see if the shrimp behave differently, and if so move the computing cluster to another room.

Thanks,
Greg

 

 

 

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It will be interesting to see if the shrimps behaviour changes with decreasing the amount of out put from your computer set up. If the system interfers with radio waves (wifi/ Bluetooth) then I wonder if the shrimps activity is also radio wave induced. Scientists suspect that empty hive syndrome with bees is down to all the  radio waves bouncing around the atmosphere now, messing with bees navigation. Aside from moving either the tank or your computer set up I don't know how else you could rectify electrical/ magnetic/ radio wave influences.

Mentioning the dogs reminded me of an article I had watched showing how dogs will circle and circle in a strange place to "correctly align" themselves prior to toileting.

I have never really had val with cherry shrimp so much but my Darwin Red Nose shrimp love hanging out in the narrow leafed val that goes like mad in my tanks. The other plant my shrimp love hanging out in and picking around is java fern attached to timber. Shrimp do like to also hang underneath in the roots of duckweed, but duckweed grows at such an amazing rate I have learnt never to let it into a shrimp tank because its almost impossible to remove the duckweed without also removing shrimplets. Duckweed also tends to clog filters. Amazon Frogbit might be a safer floating plant for a tank and has the bonus of soaking up excess nutrients.

 

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20 hours ago, gtippitt said:

I do have a large computing cluster that draw about 2500 watts when running at full capacity.  It's a case-less thing I built of 3 motherboards, 6 graphics cards, 'egg-crate' lighting diffusers, and zip ties, without any metal shielding.  With 75 CPU cores plus the GPUs

Woah !

 

20 hours ago, gtippitt said:

reates enough RFI that I have trouble with WiFi and Bluetooth in that room when it's running fully busy.

That might be the cause. It would be interesting to find out.

What would all that RFI do to humans? 

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Yesterday I powered off the nodes of my compute cluster in my living room with the fish tanks, and the shrimp continued their play / OCD.  This morning I was doing some electrical re-wiring and had all the power off, so the tanks were only running on the battery from their UPS.  After a couple of hours, with not other power in the house, their behaviour hadn't changed that I could tell.  They tend to be less active in the morning in general and become most active in the early evening.  Perhaps they take after their Papa, who's always been a nite-owl and not much of a morning person.

As for the effect of RFI on ones body, after spending a career working on voice and data system in air conditioned data centers, I have lost about half of my hearing due to noise, but that is also a result of my hobby as a sound engineer for metal bands for a decade.  My other hobby of ham radio probably exposed me to more RF than computers.  Other than my hearing loss, my other health problems are more a result of junk food, caffeine, alcohol, and chain smoking than radio waves.

The tissue of the brain is among the most easily damaged by the energy of radio waves than other parts of the body, so people who spend their lives with a cell phone to their ear or a BT device inserted as closely as possible to their brain are exposed to more damaging radiation than anyone.  Next most exposed perhaps are the people with a laptop computer transmitting WiFi, BT, and other radio waves pressed against their reproductive organs while waiting in air ports, riding a train, etc.  Someone once suggested that my ornery and asocial personality might be a result of changes in my brain from decades spent in old mainframe data centers, but I've been this way since my earliest childhood memories.

I decided later today to more closely examine the flow of the water current within the tank to see how their swimming circuit corresponded.  For this shallow 20 gallon tank, I wanted a gentle current with lots of bio media capacity.  I'm using a 5 gallon bucket filled with ceramic media with a relatively small power head inside it as the pump.  To watch the water currents within the tank, I tied a small strip of mylar ribbon on the end of a bamboo skewer and moved it slowly around the tank to watch the water flow.  It forms a slow "wheel shaped" current in the same direction as the shrimp swim, but 90 degrees perpendicular. The water flows along the top level from the left end of the tank, sinks, then flows right to left along the bottom.  The areas where I see them swimming most are the open areas where there is the least current in either directions.  There are other places in corners, around plants, and large shell where I feed them that have less current, but the area where they perform their parade is the place with the longest spaces with the least current.  

The RCS as well as the small tropical fish in my other tanks sometimes enjoy playing in the different water currents in a tanks, while at other times seeking at calm places in the water to simply "chill out".  I may sound like I'm anthropomorphizing, but I do believe any being that can feel pain can also feel joy, and sometime "plays" by doing things because it is enjoyable.  The RCS sometimes play in the very strongest currents for a while, while also seeking out the areas with very little current where they sit quietly.  I think this "parade" I'm observing is when some of them want to simply want to swim, so they've found the place in the tank where they find the best compromise of open distance and least turbulence in the currents.  Ironically when I thought about the size of the tank and the size of these shrimp, which are all less than 15mm, I realized that the route's relatively dimensions were close to that of a football field (pick your type) for a human's size.  That probably is anthropomorphizing.

The fact that I've noticed this behavior with my shrimp and others have not is probably not coincidence, but rather an indirect result of the way I set up the tank.  While I was waiting for the tank to cycle before I got the shrimp, I tinkered with the water flow and filtration a lot.  Obsessing over filtration is one of my hobbies in itself.  For about 2 weeks I had tinkered with the placement of everything in the tank to ensure that their would be some relatively quiet spaces that were not completely devoid of circulation, while creating a flow that would create a continuous and through circulation with minimal hard currents.  I do this with my fish tanks that have tetras, barbs, cory cats, etc, because they normally live in the shallow parts of streams with similar conditions.  Since the Neo's naturally live in similar conditions as well, I did the same but with a slower currents because of their size.  

Since I was cutting the flow of water of the pump to about half what I normally used per gallon of tank size, I doubled the amount of filter media.  I normally try to have about 10 to 1 ratio, so for this 20 gallon tank I used a 5 gallon filter, which I would normally use on a 55 gallon tank. Yeah it's overkill, but I never have any detectable levels of ammonia or nitrite in the tanks regardless of stocking levels or how much I feed.  Weekly 10% water changes are enough that remaining nitrates and other dissolved solids are sucked up by the plants.  If these do creep up a bit, then my huge bunch of Pothos vine visits the tank for a week or so to Hoover up gunk until the TDS are back under 200 ppm.

Since I can't find any connection to the EMI, which I thought seemed most promising since nobody else saw this behavior, I think the water flow is perhaps the best explanation.  Rather than my shrimp being OCD, it is because I am and created a specific water patter with my obsessing over the water flow in the tank.  It's also ironic because my first post on this forum was about water flow in my first shrimp tank, which was a completely and tragic failure.  Happily this second family of shrimp all seem healthy and shaming the rabbits, squirrels, and other wildlife in my yard when it comes to reproduction rates. 

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My most active shrimp right now are YKK's in a 10g with a single sponge filter on the right side with water flowing to the left. They aren't always active, but today (May 7th, actually), prior to turning on the light and hours later, after turning it off, they were all swimming around the tank. I was starting to think that I had received all males, when one of the larger shrimp finally developed a saddle... even she swims around the entire tank like somethings going on. The only ones who generally don't are the youngest shrimp... sometimes they do join in, but for the most part, they remain calm. I can't tell if they are freaking out due to hormones or what. Nothing was added to the tank out of the norm, they just occasionally swim all over the place.

On average, I would say that they are more calm and peaceful than they are rowdy and swimming all over the place.


The 20g tank (tall, not long), has an AC30 on it, and the shrimp only end up really swimming about if a female has molted.... otherwise, it's pretty calm... the AC30 is in the middle, in the back of the tank. This tank *only* contains cherry shrimp.

Then there is the 30g... which has an AC50 on it... again, back and center of the tank. The shrimp in this tank are, once again, pretty calm and quiet, like the 20g. This tank has cherry shrimp, 2 amano shrimps, and some kuhli loaches.

 

All tanks currently face north, too... in fact, the 10g sits directly below the 20g. I wonder if behavior could be changed if the AC's were moved to the side of the tank? I could do this in the 20g, but not the 30g...

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  • 2 weeks later...

I found the answer to why my shrimp were swimming in this pattern, and it was the current in the tank.  As the Amazon Sword and the Jungle Val grew bigger, I couldn’t easily see the large mussel shell that I use as their food bowl.  I decided to shift them about some since  I like to watch them eating their pellets while I have my morning coffee.  Even though I only moved the sword plant and the shell, the plant’s larger leaves were then diffusing the water flow into more random eddies as I had originally wanted from my placement of plants.  For the past 3 days since I moved the sword plant, they are no longer swimming in circles.  There still seems to be about half of them swimming about while the others rest and/or feed, but the active ones are now going from place to place randomly rather than their prior synchronized swimming. 

As the Jungle Val had grown larger, it was beginning to alter the current some as I had hoped.  The plant sprigs I had put in the tank initially were small runners I had clipped from plants in my community fish tank.  They have now grown from little things at the bottom, to now have leaves that reach the to and trail in the surface current as I had hoped.  Their movement in the currents had altered it enough that I was already noticing that fewer of the shrimp were circling the tank, and with the movement of the sword plant, its larger leaves in the center of the tank were enough to completely disrupt the prior water current.  The water in the tank still has the gentle overall flow that circulates along the top, down one end, and then back along the bottom, but its extremely gentle now and dispersed across the entire top and bottom rather than being mostly a stripe along the top and bottom.

It was odd to realize that the shrimp were swimming in a pattern analogous to a hamster running laps around its wheel rather than running on the wheel. 

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