Amano shrimp preying on Otto's?!

Panofsky

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This morning I was shocked to discover one of my Caridina Japonica dragging an Otocinclus Affinis into it's hiding! I went in with my hand to see what was going and try to scare off the Amano shrimp. He wouldn't let go, so I thought that the otto might be dead. After flicking the shrimp with my nail, the otto escaped and appeared to be healthy as ever. Did any of you ever experience this behaviour before?

Both the otto's and shrimp have been with me for over 3 years. During the years it has come to me that those busy looking shrimp aren't as cute as they appear. However, I did never expect it to hunt its tankmates. The tank is quite understocked, having only 15 cardinals, 3 amano's and 5 otto's in 200L. Well, there were 5 once, but I have noticed 2 went missing, guess why...

Anyway, I will up my feeding rate as I was dosing lean for a few months. Could this be the sole cause? Anyone who could shed light on the matter is more than welcome to chime in. In any case, take this as a warning!

For some visual stimulation, the whole ordeal looked exactly like this:

sneaky_octopus.gif
 

roadmaster

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Not many HEALTHY fishes, that could not/would not avoid Amano shrimp.
I hear these stories on the web all the time ,and cannot help but think that fishes being drug around by shrimp were weakened, or near death, lest they easily swim away.
Fully prepared now to hear the stories once more,, of shrimp attacking fishes in packs, and carrying off décor in the tank,:lol:
Seriously,the oto's primary food is algae, particularly brown algae or diatom's.
People buy these wild caught fishes for algae control and when the algae is gone,they slowly begin to decline in health possibly to the point where they starve to death.
Amanos will easily scavenge upon all manner of decaying animal or plant matter.

I liken these stories to... "The Dingo's took my baby ":wideyed:
 

Panofsky

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Hmm, I do understand what you are saying. And yes, I can imagine a weakened otto or small tetra being an easy target. However this really was a healthy otto. I have not acquired any otto's for over 2 years easily. And this one is as fat as he could be and happily schooling with other otto's. To me this is not a sign of a weakened fish. In addition, I'm not stupid, I'd never overstock a tank on otto's just to keep algae in check. There's plenty of biofilm to go around. And frankly I'm a bit disappointed you'd even suggest this. It's not your average petsmart over here.

Believe what you will, but I'm starting to think that Amano Shrimp - when adult and hungry - will actively target small fish when opportunity arises. This one succeeded because the otto in question was grazing on algae in the bottom corner of the tank.
 
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Check this out, sounds like what you're talking about.

 

Panofsky

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Check this out, sounds like what you're talking about.

How horrendous. That does look like what I was talking about. Although, my shrimp are much larger adults and the otto's are bit smaller than those in the video. Perhaps that is why my Amano successfully captured it. Anyway, those otto's in the video do look underfed. Their belly is hollow and their pretty timid. So Roadmaster's comment might not be far off. I can ensure you however that my fish are way more active and (almost) never let a shrimp catch up on it from behind.

Never saw my shrimp constantly harassing fish like this. Do you think this would be due to a lack of (hair) algae for shrimp to eat?
 

kadoxu

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Do you feed the Amanos at all?

Like fish, they shouldn't get only one type of food all the time. So you shouldn't rely solely on algae as a food source, you should provide something else once in a while.

My advice is: Get some GlasGarten Shrimp Dinner Pads or Grans and start feeding them once in a while.

I personally use pads, but in your case I would try the granular type, since it's easier to dose properly.
 
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My amanos will grab anything available. I feed my fish flakes, granules, algae wafers, catfish pellets and of course shrimp food. They don't seem to care, if they can get hold of it and take off they will.

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kadoxu

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My amanos will grab anything available. I feed my fish flakes, granules, algae wafers, catfish pellets and of course shrimp food. They don't seem to care, if they can get hold of it and take off they will.
Also true, but since the problem here seems to be lack of available food for the shrimp, I would advise feeding something big enough so that the other fish can't easily eat it right away.

The only other reason I can think of is that these shrimp are just bloodthirsty demons! :twisted:
 

Panofsky

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Do you feed the Amanos at all?

Well, yes and no. I feed a general granulate. It's a mix of floating, and fast and slow sinking granules. Circa 15% of the food hits the bottom. And although the shrimp have no competing bottom feeders it might not be enough. I'll drop in some wafers and see if that helps.
 
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I use one of the clips with suckers on and put a slice of cucumber in my tank which both the Amano and Otto enjoy. Only problem there I reckon would be you're putting the two in the same feeding area which may not help. I wonder if it's caused by Amano breeding, maybe they get a bit touchy when they're on the nest.
 

Silviu Man

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I have Amano and Oto in may aqvarium but I have never seen this. Nevertheless, Amano is eating a large kind of stuffs but is tempted also by death fish and shrimps. Are you sure Oto have no problem, maybe somthing on their skin, wounds, anything else ...?
 

alto

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I feed frozen bloodworm, brine shrimp (regular & spirilina), daphnia, Australian black worms, decaps, and some dry foods .....
AND I don't keep Amano shrimp anymore
- those large adult females can be vicious in their pursuit of food & protecting their territory, they regularly kill smaller (cherry & tiger) shrimp & harass fish, if the smaller males are up to similar activities, I seldom observe them

Juvenile amano seem much more satisfied with combing plants & substrate for food, but still tend to send other shrimp on their way rather than ignoring them

As roadmaster (& others) assume, I also assumed the fish they caught were in a weaken condition

I like my tanks rather better without their presence :)
 

Konsa

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Hi
Like everyone on here suggested the amanos need feeding on regular basis especially when couple of years old and reached the beastly size.I keep mine for years with all sorts of fish and shrimp.I have never had problem with agression towards tank mates but they destroyed a lot of plants(Dwarf lobelia particular favourite eaten to the bone) when left on algae diet only.I feed mine only blanched greens (kale ,spinach nettle...)daily for the last year and have no issues with them.I get frozen spinach and kale from supermarket and the nettle collect myself.
Give it a go it's cheap food sorse and other tank mates probably wont bother so U know they are fed.U never know U just may convert them to vegetarian lifestyle

Regards Konsa
 

xim

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Check this out, sounds like what you're talking about.

I only see that with ill fish, especially ones with skin disease. The rotting wound smell might attract them while other healthy fish are ignored. Occasionally my Oto's even chase them away while eating. But yeah, in this vid, there are more than one Oto being chased so unlikely the sick fish case.

Like others have replied, the shrimp may lack some nutrition and that evokes that behaviour. My Amano's have a big share in Cory's food.
 
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Believe what you will, but I'm starting to think that Amano Shrimp - when adult and hungry - will actively target small fish when opportunity arises. This one succeeded because the otto in question was grazing on algae in the bottom corner of the tank.

This topic has come up on the forum several times. Amanos are capable and will catch and eat healthy fish if hungry enough. There's plenty of evidence for that.
 

Mogster

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I've been re-stocking my 30G recently after having to strip it down after a leak.

Plants went in first followed by 10 glowight Danios then a week later 15 2cm or so Amanos. The Amanos like to discreetly hang out on my tall Vallis and a couple of times I've seen them attempt to drop onto the Danios as they swim past. The Danios just shake them off and continue what they're doing but I'm surprised to see the Amanos acting in such a predatory way. I quite like it... I really don't see how they could grapple anything other than a tiny slow moving fish and I'd rather they stuck up for themselves than just being simply live food for fish :)

The range of behaviour the Amanos display for such tiny animals is simply amazing.
 

jackychun218

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That behavior from Amano shrimps happened sometimes in my tank. I was shocked at first but also find out that Amano Shrimps might have ability to sense the weaker fish/snails. They will come to them like seek for food.

I then put more food for them like blanched zucchini slice time to time. So when they are full, they will not disturb others.


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SinkorSwim

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Ive seen aggressive destructive bahaviour by adult amanos and because of that, I wouldnt voluntarily keep them in a delicately planted community tank any more. But in a big planted tank as the sole inhabitants, youll not find a more dedicated clean up team. They are voracious eating machines that as I observed, only stopped feeding to search for more food.

I've personally watched in frustration and for only a short time as an adult slowly pulled up my cuba carpet lookjng for detritus, drag away shrimp food pellets away from its fellow tank inhabitants and actively chase other neo shrimp for no apparent reason. Possibly to check thevshrmp was in health and could evade. Pure speculation on my part but it's not outwith the boundaries... I eventually removed the amanos after my neo population started to decline faster than a normal mortality rate would suggest. I couldnt say for sure but im sure they were predating on their smaller cousins under cover of darkness despite me feeding before lights out. They are opportunists, albeit aggressive and possibly predatory ones.

Despite my experiences i cant blame them for their nature, and they make for amazing cleaning machines. If I ever decide to start a big iwagumi or similar, i know what crew I would look to, to aid and assist in aesthetics. But never again in a shrimp community tank.
 

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